the source of palladium contained in the catalyst to be used in the process for producing a hydrogen - containing gas according to the present invention is not specifically limited . there are usable as the source of palladium , for instance , palladium nitrate , palladium acetate , palladium chloride , dinitrodiammine palladium and the like . of these , palladium nitrate , palladium acetate and palladium chloride are preferably used . zinc oxide available on the market is usable as zinc contained in the catalyst to be used in the process for producing a hydrogen - containing gas according to the present invention . in addition , there are also usable as a zinc source , such zinc compounds that form zinc oxide after calcining or reducing or during reaction , including a salt of an organic acid or an inorganic acid such as zinc acetate and zinc nitrate , zinc hydroxide and basic zinc carbonate . for instance , zinc oxide is obtainable by calcining the precipitate obtained by treating aqueous solution of a zinc salt of an organic acid or an inorganic acid with a precipitant . the source of chromium contained in the catalyst is not specifically limited provided that it can be made into chromium oxide upon completion of catalyst preparation . there is usable as the source of chromium , for instance , a water - soluble salt of an organic acid or an inorganic acid such as chromium acetate and chromium nitrate . in this case , chromium oxide is obtainable by calcining the precipitate obtained by treating aqueous solution of the above - cited chromium compound with a precipitant , the source of gallium contained in the catalyst is not specifically limited provided that it can be made into gallium oxide upon completion of catalyst preparation . there are usable as the source of gallium , for instance , gallium hydroxide , gallium oxide , gallium nitrate and the like . as the source of copper , there is usable for instance , a water - soluble salt of an organic acid or an inorganic acid such as copper acetate , copper sulfate and copper nitrate . as the source of indium , there is usable for instance , a salt of an organic acid or an inorganic acid such as indium acetate and indium nitrate . as the source of bismuth , there is usable for instance , an inorganic acid salt such as bismuth nitrate . as the source of platinum , there are usable platinum oxide , chloroplatinic acid , an alkali metal salt thereof , acetylacetonato platinum , dinitrodiammine platinum and the like . in the case of preparing a catalyst by dissolving in water , it is preferable to employ chloroplatinic acid or an alkali metal salt thereof . with regard to the chemical composition of the catalyst to be used in the process ( i ) comprising palladium , zinc , and either or both of chromium and gallium , the atomic ratio of palladium / zinc is in the range of 0 . 004 to 2 . 2 , preferably 0 . 04 to 0 . 6 , and the atomic ratio of ( the sum of chromium and gallium )/ zinc is in the range of 0 . 03 to 2 , preferably 0 . 05 to 1 . a method for preparing the catalyst in the process ( i ) is not specifically limited provided that the method allows the metallic palladium , zinc oxide , and either or both of chromium oxide and gallium oxide to coexist . there are available , for instance , ( 1 ) a method ( coprecipitation method ) comprising simultaneously forming a precipitate from the mixed solution of a water - soluble compounds of palladium , zinc , chromium and gallium , respectively along with a precipitant ; ( 2 ) a method comprising mixing the slurry in which zinc oxide , zinc hydroxide , basic zinc carbonate or the like is dispersed with a solution of compounds of palladium , chromium and gallium , respectively , and adding a precipitant or a reducing agent to the resultant mixture to deposit components of palladium , chromium and gallium , respectively ; and ( 3 ) a method comprising preparing a composition composed principally of palladium and zinc oxide through coprecipitation method or the like , and impregnating a chromium compound and a gallium compound into the resultant composition ; ( 4 ) a method comprising preparing a composition composed principally of palladium and zinc oxide through coprecipitation method or the like , mixing the slurry wherein the resultant composition is dispersed with a solution of a chromium compound and a gallium compound , and adding a precipitant to the resultant mixture to deposit components of chromium and gallium ; and ( 5 ) a method comprising preparing a composition composed principally of zinc , chromium and gallium through coprecipitation method or the like , mixing the slurry wherein the resultant composition is dispersed with a solution of a palladium compound , and adding a precipitant or reducing agent to the resultant mixture to deposit a palladium component ; and the like method . as a precipitant to be used in the preparation of the catalyst , use is made of an alkali compound such as sodium hydroxide , potassium hydroxide , sodium carbonate , potassium carbonate and sodium hydrogencarbonate . the amount of the precipitant to be used therein is one to 2 times , preferably 1 . 1 to 1 . 6 times the chemical equivalent weight . the temperature at the time of preparing a precipitate is 20 to 90 ° c ., preferably 35 to 85 ° c . it is preferable to wash the precipitate obtained by precipitation method with ion - exchanged water , distilled water or the like . the resultant slurry obtained by the above - mentioned method is dried or dried / calcined , crushed , uniformized in size or molded , and then put into service . it is also possible to support the intact slurry thus obtained on a carrier or a carrier structure , or to add a binder such as alumina sol thereto at need , and thereafter support the binder - treated slurry thereon . in this case it is possible to use the supported catalyst after drying and as such or after drying and calcining . the drying temperature is preferably in the range of 50 to 150 ° c . the calcination is carried out in air at a temperature in the range of 180 to 700 ° c ., preferably 200 to 600 ° c . a method for preparing the catalyst to be used in the process ( ii ) ( comprising palladium , copper , zinc and chromium ) is not specifically limited provided that palladium , copper , zinc oxide and chromium oxide are each made to be a principal ingredient . for instance , the catalyst is prepared by depositing and precipitating palladium and copper in a composition composed principally of a zinc compound and a chromium compound , and drying calcining the resultant precipitate . the type and amount of the precipitant to be used therein and drying calcining method are same as those in the above - mentioned method ( i ). with regard to the chemical composition of the catalyst to be used in the process ( ii ), the atomic ratio of chromium / zinc is in the range of 0 . 03 to 2 , preferably 0 . 05 to 1 , the atomic ratio of palladium / zinc is in the range of 0 . 004 to 2 . 2 , preferably 0 . 04 to 0 . 6 , and the atomic ratio of copper / zinc is in the range of 0 . 01 to 1 . 6 , preferably 0 . 05 to 0 . 6 . as a method for preparing the catalyst to be used in the process ( iii ) ( comprising palladium and zinc , or chromium added thereto optionally , and either or both of indium and bismuth ), there are usable well known methods such as impregnation method , deposition - precipitation method , coprecipitation method and the like methods provided that ( 1 ) the system of metallic palladium , zinc oxide , indium oxide and bismuth oxide or ( 2 ) the system of metallic palladium , zinc oxide , chromium oxide , indium oxide and bismuth oxide is contained in the reaction system in a closely mixed state . there are available , for instance , ( a ) a method ( deposition - precipitation method ) comprising treating with a precipitant , ( 1 ) a mixed aqueous solution containing a water - soluble zinc salt , an indium salt and a bismuth salt or ( 2 ) a mixed aqueous solution containing a water - soluble zinc salt , a chromium salt , an indium salt and a bismuth salt to obtain a precipitate , drying and calcining the resultant precipitate , thereafter mixing the suspension of the calcined product with a solution of a soluble palladium salt , adding a precipitant to the resultant mixture to deposit and precipitate the mixture , and drying calcining the deposited precipitate ; and ( b ) a method ( coprecipitation method ) comprising treating with a precipitant , ( 1 ) a mixed aqueous solution containing a water - soluble palladium salt , a zinc salt , an indium salt and a bismuth salt or ( 2 ) a mixed aqueous solution containing a water - soluble palladium salt , a zinc salt , a chromium salt , an indium salt and a bismuth salt to obtain a precipitate , drying and calcining the resultant precipitate , and the like methods . the type and amount of the precipitant to be used therein and drying calcining method are same as those in the above - mentioned method ( i ). with regard to the chemical composition of the catalyst to be used in the process ( iii ), the atomic ratio of palladium / zinc is in the range of 0 . 004 to 2 . 2 , preferably 0 . 04 to 0 . 6 , the atomic ratio of chromium / zinc is in the range of 0 . 03 to 2 , preferably 0 . 05 to 1 , the atomic ratio of indium / zinc is in the range of 0 . 025 to 2 ., preferably 0 . 03 to 1 , and the atomic ratio of bismuth / zinc is in the range of 0 . 0025 to 20 , preferably 0 . 003 to 1 . a method for preparing the catalyst ( comprising zinc oxide , palladium and platinum ) in the process ( iv ) is not specifically limited provided that the method allows the zinc oxide , palladium and platinum to coexist . there are available , for instance , ( 1 ) a method ( coprecipitation method ) comprising simultaneously forming a precipitate from the mixed solution of a water - soluble compounds of zinc , platinum and palladium , respectively along with a precipitant ; ( 2 ) a method comprising mixing the slurry in which zinc oxide or zinc hydroxide or basic zinc carbonate is dispersed with a solution of compounds of platinum and palladium , respectively , and adding a precipitant or a reducing agent to the resultant mixture to deposit components of platinum and palladium , respectively ; and ( 3 ) a method comprising impregnating a palladium compound and a platinum compound into zinc oxide or zinc hydroxide or basic zinc carbonate . the type and amount of the precipitant to be used therein and drying calcining method are same as those in the above - mentioned method ( i ). with regard to the chemical composition of the catalyst to be used in the process ( iv ) expressed in terms of the percentage of the number of metallic atoms based on the number of the total metallic atoms and oxygen constituting the catalyst , there are contained zinc in 10 to 50 %, preferably 20 to 50 %, platinum in 0 . 01 to 30 %, preferably 0 . 1 to 24 % and palladium in 0 . 01 to 40 %, preferably 0 . 05 to 30 %. the ratio of palladium to platinum is not specifically limited , but can be optimized in accordance with the durability of the catalyst , performance required of the production process such as carbon monoxide concentration in the outlet gas and reaction conditions . with regard to the auto thermal system reaction wherein methanol , steam and air are reacted , an activation treatment may be carried out , for instance , with hydrogen , carbon monoxide - containing gas or the like as is the case with the steam - reforming reaction . it is also possible to proceed with the reaction without such an activation treatment . the reaction conditions in the case of reacting methanol , steam and air are such that a molar ratio of steam to methanol is 1 to 10 mol , preferably 1 to 5 mol , a molar ratio of air to methanol is 0 . 3 to 5 . 0 mol , preferably 0 . 5 to 3 . 0 mol , a reaction temperature is in the range of 150 to 600 ° c ., preferably 200 to 500 ° c ., a reaction pressure is at most 0 . 5 mpa - g , preferably in the range of atmospheric pressure to 0 . 5 mpa , and a liquid hourly space velocity ( lhsv ) of methanol per unit volume of catalyst used is 0 . 1 to 120 h − 1 , preferably 0 . 5 to 100 h − 1 . in summarizing the working effects and advantages of the methanol - reforming reaction according to the present invention , it is made possible by the use of the specific catalyst to improve the durability of the catalyst in the process ( i ), the durability of the catalyst and selectivity ( lowering of carbon monoxide concentration ) in the process ( ii ), selectivity in the process ( iii ) and the durability thereof along with its suitability for use in an auto thermal reformer in the process ( iv ). accordingly the process according to the present invention enables the production of a hydrogen - containing gas in an industrially advantageous manner . in what follows , the present invention will be described in more detail with reference to comparative examples and working examples , which however shall never limit the present invention thereto . in the following comparative examples and working examples , reactivity of methanol and selectivity to carbon monoxide were determined from the chemical composition of the gas at the outlet of the reactor . in the formulae , [ co ], [ co 2 ] and [ ch 3 oh ] are molar concentration of co , co 2 and ch 3 oh , respectively in the gas at the outlet of the reactor . sodium carbonate anhydride in an amount of 204 g and 200 milliliter ( ml ) of ion - exchanged water were placed in a 5 liter round bottom flask to dissolve the sodium carbonate , and adjusted to a temperature of 40 ° c . to the resultant solution was added an a solution of 26 g of palladium nitrate 1 . 9 - hydrate , 298 g of zinc nitrate hexahydrate and 100 g of chromium nitrate nonahydrate that were dissolved in 1000 ml of ion - exchanged water , while the solution was adjusted to 40 ° c ., followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 12 liter of ion - exchanged water . subsequently the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — zn — cr . the resultant catalyst was wet crushed , mixed with alumina sol to be made into slurry . subsequently , there were repeated the steps of immersing a honeycomb ( 400 cells / square inch ) made of cordierite ( cordierite porcelain ) into the slurried catalyst , blowing off an excess amount and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst a - 1 having a chemical composition expressed in terms of atomic ratio of pd / zn / cr being 0 . 1 / 1 . 0 / 0 . 25 . sodium carbonate anhydride in an amount of 138 g and 1000 ml of ion - exchanged water were placed in a 5 liter round bottom flask to dissolve the sodium carbonate , and the resultant solution was adjusted to a temperature of 60 ° c . to the resultant solution was added a solution of 238 g of zinc nitrate hexahydrate and 80 g of chromium nitrate nonahydrate that were dissolved in 800 ml of ion - exchanged water , while the solution was adjusted to 60 ° c ., followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 12 liter of ion - exchanged water . subsequently the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain zn — cr oxide . the resultant 100 g of zn — cr oxide and 1000 ml of ion - exchanged water were placed in a 5 liter round bottom flask to disperse the zn — cr oxide , and adjusted to a temperature of 40 ° c . subsequently to the resultant dispersion were added a solution of 26 g of palladium nitrate 1 . 9 - hydrate dissolved in 2000 ml of ion - exchanged water , while the solution was adjusted to 40 ° c ., and 50 ml of aqueous solution of 20 % by weight of sodium carbonate , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 12 liter of ion - exchanged water . subsequently the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — zn — cr . in the same manner as in catalyst a - 1 , the catalyst of pd — zn — cr was supported on a honeycomb ( 400 cells / square inch ) made of cordierite so as to be supported in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst b - 1 having a chemical composition expressed in terms of atomic ratio of pd / zn / cr being 0 . 11 / 1 . 0 / 0 . 25 . in the same manner as in catalyst b - 1 , a catalyst of pd — zn — cr was prepared except that pd / zn ratio was set on 0 . 05 . in the same manner as in catalyst a - 1 , the catalyst of pd — zn — cr was supported on a honeycomb ( 400 cells / square inch ) made of cordierite so as to be supported in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst c - 1 having a chemical composition expressed in terms of atomic ratio of pd / zn / cr being 0 . 05 / 1 . 0 / 0 . 25 . in the same manner as in catalyst b - 1 , a catalyst of pd — zn — cr was prepared except that pd / zn ratio was set on 0 . 24 . in the same manner as in catalyst a - 1 , the catalyst of pd — zn — cr was supported on a honeycomb ( 400 cells / square inch ) made of cordierite so as to be supported in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst d - 1 having a chemical composition expressed in terms of atomic ratio of pd / zn / cr being 0 . 24 / 1 . 0 / 0 . 25 . zinc oxide in an amount of 15 g was dispersed in 500 ml of ion - exchanged water , and the dispersion was adjusted to a temperature of 35 ° c . to the resultant dispersion were added under stirring , an aqueous solution of 4 . 17 g of palladium nitrate dihydrate dissolved in 500 ml of ion - exchanged water which solution had been adjusted to a temperature of 35 ° c ., and 35 ml of 1 n aqueous solution of potassium hydroxide , followed by continuous stirring for 1 hour to form a precipitate . the resultant precipitate was filtered to form a cake , which was washed with 4 liter of ion - exchanged water . subsequently the washed cake was dispersed in 500 ml of ion - exchanged water , and adjusted to a temperature of 35 ° c . to the resultant dispersion were added an aqueous solution of 5 . 26 g of gallium nitrate hydrate dissolved in 500 ml of ion - exchanged water which solution had been adjusted to a temperature of 35 ° c ., and 37 ml of 1 n aqueous solution of potassium hydroxide , followed by continuous stirring for 1 hour to form a precipitate . the resultant precipitate was dried , and then was calcined to obtain a catalyst of pd — zn — ga . the resultant catalyst was wet crushed , and mixed with alumina sol to be made into slurry . subsequently there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst d - 1 having a chemical composition expressed in terms of atomic ratio of pd / zn / ga being 0 . 08 / 1 . 0 / 0 . 07 . potassium carbonate in an amount of 34 . 5 g was dissolved in 500 ml of ion - exchanged water , and the solution was adjusted to a temperature of 60 ° c . to the resultant solution was gradually added under stirring , an aqueous solution of 57 . 6 g of zinc nitrate hexahydrate and 5 . 53 g of gallium nitrate nonahydrate that were dissolved in 500 ml of ion - exchanged water which solution had been adjusted to a temperature of 60 ° c ., followed by continuous stirring for 1 hour , while keeping the temperature at 60 ° c . to form a precipitate . the resultant precipitate was filtered to form a cake , which was washed with 4 liter of ion - exchanged water . subsequently the washed cake was dried , and then was calcined to obtain a zinc - gallium compound . the resultant compound was crushed , dispersed in in 500 ml of ion - exchanged water , and adjusted to a temperature of 35 ° c . to form slurry . to the resultant slurry were added under stirring , an aqueous solution of 4 . 17 g of palladium nitrate dihydrate dissolved in 500 ml of ion - exchanged water which solution had been adjusted to a temperature of 35 ° c ., and then 35 ml of 1 n aqueous solution of potassium hydroxide , followed by continuous stirring for 1 hour to form a precipitate . the resultant precipitate was filtered to form a cake , which was washed with 4 liter of ion - exchanged water . subsequently the washed cake was dried , and thereafter was calcined to obtain a catalyst of pd — zn — ga . the resultant catalyst was wet crushed , and mixed with alumina sol to be made into slurry . subsequently there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst f - 1 having a chemical composition expressed in terms of atomic ratio of pd / zn / ga being 0 . 09 / 1 . 0 / 0 . 07 . zinc oxide in an amount of 15 g and 500 ml of ion - exchanged water were placed in a 2 liter beaker to disperse zinc oxide . to the resultant dispersion were added an aqueous solution of 4 . 3 g of palladium nitrate 2 . 3 - hydrate dissolved in 500 ml of ion - exchanged water , and 32 ml of 1 n aqueous solution of potassium hydroxide , followed by stirring for 30 minutes to form slurry . the resultant slurry was filtered to form a cake , which was washed with 5 liter of ion - exchanged water . subsequently the washed cake was dried , and then was calcined to obtain a catalyst of pd — zn . in the same manner as in catalyst a - 1 , the catalyst of pd — zn was supported on a honeycomb ( 400 cells / square inch ) made of cordierite so as to be supported in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst g - 1 having a chemical composition expressed in terms of atomic ratio of pd / zn being 0 . 09 / 1 . 0 . zinc oxide in an amount of 15 g was dispersed in 500 ml of ion - exchanged water , and the dispersion was adjusted to a temperature of 35 ° c . to the resultant dispersion were added under stirring , an aqueous solution of 4 . 17 g of palladium nitrate dihydrate dissolved in 500 ml of ion - exchanged water which solution had been adjusted to a temperature of 35 ° c ., and 35 ml of 1 n aqueous solution of potassium hydroxide , followed by continuous stirring for 1 hour to form a precipitate . the resultant precipitate was filtered to form a cake , which was washed with 4 liter of ion - exchanged water . subsequently the washed cake was dried , and then was calcined to obtain a catalyst of pd — zn . the resultant catalyst was wet milled , and mixed with alumina sol to be made into slurry . subsequently there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst h - 1 having a chemical composition expressed in terms of atomic ratio of pd / zn being 0 . 085 / 1 . 0 . gallium oxide ( ga 2 o 3 ) in an amount of 15 g was dispersed in 500 ml of ion - exchanged water , and the dispersion was adjusted to a temperature of 35 ° c . to the resultant dispersion were added under stirring , an aqueous solution of 4 . 17 g of palladium nitrate dihydrate dissolved in 500 ml of ion - exchanged water which solution had been adjusted to a temperature of 35 ° c ., and 35 ml of 1 n aqueous solution of potassium hydroxide , followed by continuous stirring for 1 hour to form a precipitate . the resultant precipitate was filtered to form a cake , which was washed with 4 liter of ion - exchanged water . subsequently the washed cake was dried , and then was calcined to obtain a catalyst of pd — ga . the resultant catalyst was wet crushed , and mixed with alumina sol to be made into slurry . subsequently there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst i - 1 having a chemical composition expressed in terms of atomic ratio of pd / ga being 0 . 1 / 1 . 0 . any of the catalysts a - 1 , b - 1 and g - 1 , prior to activity evaluation , was subjected to a reduction treatment at 200 ° c . at an lhsv ( liquid hourly space velocity ) of methanol of 5 hr − 1 . thereafter an aqueous solution of methanol having a water / methanol ratio of 1 . 5 was introduced in a evaporator at an lhsv of methanol of 15 hr − 1 instead of 5 hr − 1 . air was mixed in evaporated water / methanol on the downstream side of the evaporator outlet , and the temperature in the introduction line leading to a catalyst bed was regulated so that the mixed water / methanol vapor was charged in the catalyst bed at 200 ° c . the reaction of water / methanol was carried out at an air / methanol ratio of 0 . 9 to 1 . 2 . the chemical composition of the gas after the reaction was analyzed by means of gas chromatography . the reactivity of methanol after a reaction time of zero hour ( immediately after the start of reaction ) and 40 hours is given in table 1 , and carbon monoxide concentration at the outlet of the catalyst bed after a reaction time of the same is given in table 2 . as can be seen from tables 1 and 2 , both the catalysts a - 1 and b - 1 , as compared with the catalyst g - 1 , are excellent in durability because of less change with the lapse of time regarding both methanol reactivity and co concentration . any of the catalysts b - 1 , c - 1 , d - 1 and g - 1 , prior to activity evaluation , was subjected to a reduction treatment at 200 ° c . at an lhsv of methanol of 5 hr − 1 . thereafter an aqueous solution of methanol having a water / methanol ratio of 1 . 5 was introduced in a evaporator at an lhsv of methanol of 87 hr − 1 instead of 5 hr − 1 . air was mixed in evaporated water / methanol on the downstream side of the evaporator outlet , and the temperature in the introduction line leading to the catalyst bed was regulated so that the mixed water / methanol vapor was charged therein at 200 ° c . the reaction of water / methanol was carried out at an air / methanol ratio of 0 . 9 to 1 . 2 . the chemical composition of the gas after the reaction was analyzed by means of gas chromatography . the reactivity of methanol after a reaction time of zero hour and 40 hours is given in table 3 , and carbon monoxide concentration at the outlet of the catalyst bed after a reaction time of the same is given in table 4 . as can be seen from tables 3 and 4 , the catalysts b - 1 , c - 1 and d - 1 , as compared with the catalyst g - 1 , are excellent in durability because of less change with the lapse of time regarding both methanol reactivity and co concentration . any of the catalysts e - 1 , f - 1 , h - 1 and i - 1 was packed in a reactor and , prior to activity evaluation , was subjected to a reduction treatment at 200 ° c . at an lhsv of methanol of 15 hr − 1 . thereafter an aqueous solution of methanol having a water / methanol ratio of 1 . 5 was introduced in a evaporator at an lhsv unchanged . air was mixed in evaporated water / methanol on the downstream side of the evaporator outlet , and the temperature in the introduction line leading to the catalyst bed was regulated so that the mixed water / methanol vapor was charged therein at 200 ° c . the reaction of water / methanol was regulated so that the temperature at the inlet of the catalyst bed was made to be 400 ° c . the chemical composition of the gas after the reaction was analyzed by means of gas chromatography . as the results of the reaction , the reactivity of methanol is given in table 5 , and carbon monoxide concentration at the outlet of the catalyst bed is given in table 6 . sodium carbonate anhydride in an amount of 138 g and 1000 ml of ion - exchanged water were placed in a 5 liter round bottom flask to dissolve the sodium carbonate , and solution was adjusted to a temperature of 60 ° c . to the resultant solution was added a solution of 238 g of zinc nitrate hexahydrate and 80 g of chromium nitrate nonahydrate that were dissolved in 800 ml of ion - exchanged water , while the solution was adjusted to 60 ° c ., followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 12 liter of ion - exchanged water . subsequently the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a zn — cr oxide . the resultant 100 g of the zn — cr oxide and 1000 ml of ion - exchanged water were placed in a 5 liter round bottom flask to disperse the zn — cr oxide , and adjusted to a temperature of 60 ° c . then , to the resultant dispersion were added a solution of 26 g of palladium nitrate 2 . 5 - hydrate and 19 g of copper nitrate trihydrate that were dissolved in 2000 ml of ion - exchanged water , while the solution was adjusted to 60 ° c ., and 95 ml of aqueous solution of 20 % by weight of sodium carbonate , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 12 liter of ion - exchanged water . subsequently the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — cu — zn — cr . the resultant catalyst of pd — cu — zn — cr was wet crushed , and mixed with alumina sol to be made into slurry . subsequently there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst a - 2 having a chemical composition expressed in terms of atomic ratio of pd / cu / zn / cr being 0 . 11 / 0 . 09 / 1 . 0 / 0 . 25 . in the same manner as in the catalyst g - 1 , a catalyst was prepared . it was designated as catalyst b - 2 . in the same manner as in the catalyst a - 2 , a zn — cr oxide was obtained . the resultant 100 g of the zn — cr oxide and 1000 ml of ion - exchanged water were placed in a 5 liter round bottom flask to disperse the zn — cr oxide , and adjusted to a temperature of 60 ° c . subsequently to the resultant dispersion were added a solution of 26 g of palladium nitrate 1 . 9 - hydrate dissolved in 2000 ml of ion - exchanged water , while the solution was adjusted to 60 ° c ., and 95 ml of aqueous solution of 20 % by weight of sodium carbonate , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 12 liter of ion - exchanged water . subsequently the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — zn — cr . in the same manner as in catalyst a - 2 , the catalyst of pd — zn — cr was supported on a honeycomb ( 400 cells / square inch ) made of cordierite so as to be supported in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst c - 2 having a chemical composition expressed in terms of atomic ratio of pd / zn / cr being 0 . 11 / 1 . 0 / 0 . 25 . any of the catalysts a - 2 , b - 2 and c - 2 , prior to activity evaluation , was subjected to a reduction treatment at 200 ° c . at an lhsv of methanol of 5 hr − 1 . thereafter an aqueous solution of methanol having a water / methanol ratio of 1 . 5 was introduced in a evaporator at an lhsv of methanol of 22 hr − 1 instead of 5 hr − 1 . air was mixed in evaporated water / methanol on the downstream side of the evaporator outlet , and the temperature in the introduction line leading to the catalyst bed was regulated so that the mixed water / methanol vapor was charged therein at 200 ° c . the reaction of water / methanol was carried out at an air / methanol ratio of 0 . 8 to 1 . 2 . the chemical composition of the gas after the reaction was analyzed by means of gas chromatography . the reactivity of methanol after a reaction time of zero hour ( immediately after the start of reaction ) and 100 hours is given in table 7 , and carbon monoxide concentration at the outlet of the catalyst bed after a reaction time of the same is given in table 8 . as can be seen from tables 7 and 8 , the catalyst a - 2 , as compared with the catalysts b - 2 and c - 2 , exhibits low co concentration and high selectivity and is excellent in durability because of less change with the lapse of time regarding both methanol conversion and co concentration . sodium carbonate anhydride in an amount of 31 g and 1000 ml of ion - exchanged water were placed in a 2 liter beaker to dissolve sodium carbonate . to the resultant solution was added a solution of 62 g of zinc nitrate hexahydrate and 8 g of indium nitrate trihydrate that were dissolved in 800 ml of ion - exchanged water , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 3 liter of ion - exchanged water . thereafter , the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a zn — in oxide . subsequently , 4 g of palladium nitrate 2 . 2 - hydrate and 800 ml of ion - exchanged water were placed in a 1 liter beaker to dissolve the same . to the resultant solution was added a dispersion of 15 g of the above - prepared zn — in oxide in 200 ml of ion - exchanged water , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 3 liter of ion - exchanged water . thereafter , the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — zn — in . the resultant catalyst was wet crushed by means of a ball mill , and mixed with alumina sol in an amount of 4 % by weight as a binder to be made into slurry . subsequently there were repeated the steps of immersing a cordierite - made honeycomb having a diameter of 25 mm , a length of 5 mm and 400 cells / square inch into the resultant slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 0 . 5 g on a dry base . it was designated as catalyst a - 3 having a chemical composition expressed in terms of atomic ratio of pd / zn / in being 0 . 10 / 1 . 0 / 0 . 11 . sodium carbonate anhydride in an amount of 32 g and 1000 ml of ion - exchanged water were placed in a 2 liter beaker to dissolve sodium carbonate . to the resultant solution was added 800 ml of mixed solution composed of a solution of 55 g of zinc nitrate hexahydrate dissolved in 500 ml of ion - exchanged water and a solution of 22 g of bismuth nitrate pentahydrate dissolved in 300 ml of 2 mol / l aqueous solution of nitric acid , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 4 liter of ion - exchanged water . thereafter , the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a zn — bi oxide . subsequently , 1 g of palladium nitrate 2 . 2 - hydrate and 800 ml of ion - exchanged water were placed in a 1 liter beaker to dissolve palladium nitrate . to the resultant solution was added a dispersion of 11 g of the above - prepared zn — bi oxide in 200 ml of ion - exchanged water , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 3 liter of ion - exchanged water . the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — zn — bi . subsequently in the same manner as in the catalyst a - 3 , the catalyst of pd — zn — bi thus prepared was supported on a cordierite - made honeycomb . it was designated as catalyst b - 3 having a chemical composition expressed in terms of atomic ratio of pd / zn / bi being 0 . 15 / 1 . 0 / 0 . 25 . sodium carbonate anhydride in an amount of 40 g and 1000 ml of ion - exchanged water were placed in a 2 liter beaker to dissolve sodium carbonate . to the resultant solution was added a solution of 6 g of palladium nitrate 2 . 2 - hydrate , 55 g of zinc nitrate hexahydrate , 18 g of chromium nitrate nonahydrate and 8 g of indium nitrate trihydrate that were dissolved in 800 ml of ion - exchanged water , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 3 liter of ion - exchanged water . thereafter , the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — zn — cr — in . subsequently in the same manner as in the catalyst a - 3 , the catalyst of pd — zn — cr — in was supported on a cordierite - made honeycomb . it was designated as catalyst c - 3 having a chemical composition expressed in terms of atomic ratio of pd / zn / cr / in being 0 . 12 / 1 . 0 / 0 . 25 / 0 . 125 . sodium carbonate anhydride in an amount of 39 g and 1000 ml of ion - exchanged water were placed in a 2 liter beaker to dissolve sodium carbonate . to the resultant solution was added 800 ml of mixed solution composed of a solution of 5 g of palladium nitrate 2 . 2 - hydrate , 55 g of zinc nitrate hexahydrate and 18 g of chromium nitrate nonahydrate that were dissolved in 770 ml of ion - exchanged water and a solution of 1 g of bismuth nitrate pentahydrate dissolved in 30 ml of 2 mol / l aqueous solution of nitric acid , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 3 liter of ion - exchanged water . thereafter , the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — zn — cr — bi . subsequently in the same manner as in the catalyst a - 3 , the catalyst of pd — zn — cr — bi was supported on a cordierite - made honeycomb . it was designated as catalyst d - 3 having a chemical composition expressed in terms of atomic ratio of pd / zn / cr / bi being 0 . 11 / 1 . 0 / 0 . 25 / 0 . 0125 zinc oxide available from seido chemical industries co ., ltd . under the trade name “ azo ” in an amount of 15 g was calcined at 380 ° c . for 2 hours . the calcined zinc oxide and 500 ml of ion - exchanged water were placed in a 1 liter beaker to disperse the same . to the resultant dispersion was added a solution of 4 g of palladium nitrate 2 . 5 - hydrate dissolved in 500 ml of ion - exchanged water , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 3 liter of ion - exchanged water . thereafter , the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — zn . subsequently in the same manner as in the catalyst a - 3 , the catalyst of pd — zn was supported on a cordierite - made honeycomb . it was designated as catalyst e - 3 having a chemical composition expressed in terms of atomic ratio of pd / zn being 0 . 085 / 1 . 0 . sodium carbonate anhydride in an amount of 35 g and 1000 ml of ion - exchanged water were placed in a 2 liter beaker to dissolve sodium carbonate . to the resultant solution was added 800 ml of a solution of 55 g of zinc nitrate hexahydrate and 18 g of chromium nitrate nonahydrate that were dissolved in 800 ml of ion - exchanged water , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 3 liter of ion - exchanged water . thereafter , the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a zn — cr oxide . subsequently , 4 g of palladium nitrate 2 . 2 - hydrate and 800 ml of ion - exchanged water were placed in a 1 liter beaker to dissolve the same . to the resultant solution was added a dispersion of the above - prepared 15 g of zn — cr oxide in 200 ml of ion - exchanged water , followed by stirring for 30 minutes to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 3 liter of ion - exchanged water . thereafter , the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 380 ° c . for 2 hours in air to obtain a catalyst of pd — zn — cr . subsequently in the same manner as in the catalyst a - 3 , the catalyst of pd — zn — cr was supported on a cordierite - made honeycomb . it was designated as catalyst f - 3 having a chemical composition expressed in terms of atomic ratio of pd / zn / cr being 0 . 10 / 1 . 0 / 0 . 25 . any of the catalysts a - 3 , b - 3 , and e - 3 was placed as a catalyst bed in a through flow system reactor . the catalyst activity was evaluated based on auto thermal system reaction by passing water / methanol / air through the reactor at a water / methanol ratio of 1 . 5 , an lhsv of methanol of 87 hr − 1 , a gas temperature at the inlet of the catalyst bed being 200 ° c . and an air / methanol ratio in the range of 0 . 9 to 1 . 3 under atmospheric pressure . the chemical composition of the gas after the reaction was analyzed by means of gas chromatography . in particular , durability tests of the catalysts were carried out by regulating the methanol reactivity in the initial stage to 90 %. the reactivity of methanol after a reaction time of zero hour ( immediately after the start of the reaction ) and 40 hours is given in table 9 , and carbon monoxide concentration at the outlet of the catalyst bed after a reaction time of the same and selectivity to co are given in table 10 . as can be seen from tables 9 and 10 , both the catalysts a - 3 and b - 3 , as compared with the catalyst e - 3 , are improved in selectivity to steam - reforming reaction of methanol , and exhibit low co concentration in the hydrogen - containing gas obtained through the reforming process . any of the catalysts c - 3 , d - 3 , and f - 3 was placed as a catalyst bed in a through flow system reactor . the catalyst activity was evaluated based on auto thermal system reaction by passing water / methanol / air through the reactor at a water / methanol ratio of 1 . 5 , an lhsv of methanol of 87 hr − 1 , a gas temperature at the inlet of the catalyst bed being 200 ° c . and an air / methanol ratio in the range of 0 . 9 to 1 . 3 under atmospheric pressure . the chemical composition of the gas after the reaction was analyzed by means of gas chromatography . in particular , durability tests of the catalysts were carried out by regulating the methanol reactivity in the initial stage to 90 %. the reactivity of methanol after a reaction time of zero hour ( immediately after the start of the reaction ) and 40 hours is given in table 11 . carbon monoxide concentration at the outlet of the catalyst bed and selectivity to co each after a reaction time of 0 and 40 hours are given in table 12 . as can be seen from tables 11 and 12 , both the catalysts c - 3 and d - 3 , as compared with the catalyst f - 3 , are improved in selectivity to steam - reforming reaction of methanol , and exhibit low co concentration in the hydrogen - containing gas obtained through the reforming process . zinc oxide in an amount of 15 g was dispersed in 500 ml of ion - exchanged water . moreover , 500 ml of ion - exchanged water and 10 ml of 1 n hydrochloric acid were added to 1 . 77 g of potassium chloroplatinate and 1 . 38 g of palladium chloride to dissolve the two components , while adjusting the temperature of the resultant solution to 65 ° c . to the above - prepared dispersion of zinc oxide were added the aqueous solution of the potassium chloroplatinate and palladium chloride under stirring , and then 40 ml of 1 n aqueous solution of potassium hydroxide , while adjusting the temperature of the resultant mixture to 65 ° c . under continuous stirring for 1 hour to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 10 liter of ion - exchanged water . subsequently the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 400 ° c . to obtain a catalyst of pd — pt — zn ( pd / pt : 1 . 8 ). the resultant catalyst of pd — pt — zn was wet crushed , and mixed with alumina sol to be made into slurry . subsequently , there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst a - 4 having a chemical composition expressed in terms of atomic ratio of pd / pt / zn being 0 . 04 / 0 . 02 / 1 . 0 . zinc oxide in an amount of 15 g was dispersed in 500 ml of ion - exchanged water . moreover , 500 ml of ion - exchanged water and 10 ml of 1 n hydrochloric acid were added to 0 . 89 g of potassium chloroplatinate and 2 . 08 g of palladium chloride to dissolve the two components , while adjusting the temperature of the resultant solution to 65 ° c . to the above - prepared dispersion of zinc oxide were added the aqueous solution of the potassium chloroplatinate and palladium chloride under stirring , and then 44 ml of 1 n aqueous solution of potassium hydroxide , while adjusting the temperature of the resultant mixture to 65 ° c . under continuous stirring for 1 hour to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 10 liter of ion - exchanged water . thereafter the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 400 ° c . to obtain a catalyst of pd — pt — zno ( pd / pt : 5 . 5 ). the resultant catalyst of pd — pt — zn was wet crushed , and mixed with alumina sol to be made into slurry . subsequently , there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst b - 4 having a chemical composition expressed in terms of atomic ratio of pd / pt / zn being 0 . 06 / 0 . 01 / 1 . 0 . potassium carbonate in an amount of 29 . 5 g was dispersed in 500 ml of ion - exchanged water , and adjusted to a temperature of 65 ° c . moreover , 500 ml of ion - exchanged water and 5 ml of 1 n hydrochloric acid were added to 54 . 8 g of zinc nitrate hexahydrate , 2 . 66 g of potassium chloroplatinate and 0 . 69 g of palladium chloride to dissolve the three components , while adjusting the temperature of the resultant solution to 65 ° c . to the above - prepared solution of potassium carbonate was added the aqueous solution of the zinc nitrate , potassium chloroplatinate and palladium chloride under stirring , followed by continuous stirring for 1 hour to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 10 liter of ion - exchanged water . thereafter the washed cake was dried at a temperature of 80 ° c ., and then was calcined at 400 ° c . to obtain a catalyst of pd — pt — zn ( pd / pt : 0 . 6 ). the resultant catalyst of pd — pt — zn was wet crushed , and mixed with alumina sol to be made into slurry . subsequently , there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst c - 4 having a chemical composition expressed in terms of atomic ratio of pd / pt / zn being 0 . 02 / 0 . 35 / 1 . 0 . sodium carbonate anhydride in an amount of 177 g and 1000 ml of ion - exchanged water were placed in a 5 liter round bottom flask to dissolve the sodium carbonate , and the solution was adjusted to a temperature of 40 ° c . to the resultant solution was added a solution of 315 g of copper sulfate pentahydrate and 19 . 7 g of boric acid that were dissolved in 800 ml of ion - exchanged water , while the solution was adjusted to 40 ° c . subsequently to the resultant mixed solution was added the slurry in which 77 . 0 g of zinc oxide was dispersed in 300 ml of ion - exchanged water , and immediately thereafter carbon dioxide gas was blown thereinto at a rate of 6 liter / hour . after one hour , the temperature thereof was raised to 80 ° c ., and maintained thereat for 30 minutes . the carbon dioxide gas blowing was stopped after 2 hours of blowing , and then the mixture was cooled 60 ° c . to the cooled mixture was added the slurry which had been prepared from a solution of 49 g of aluminum sulfate dissolved in ion - exchanged water and a solution of 10 . 2 g of sodium hydroxide dissolved in 70 ml of ion - exchanged water under stirring for 20 minutes . the mixed slurry thus prepared was filtered to form a cake , which was washed with 12 liter of 0 . 05 % aqueous solution of sodium hydroxide and 3 liter of ion - exchanged water . thereafter the washed cake was dried at a temperature of 80 ° c ., and then was calcined to obtain a catalyst of cu — zn — al . the resultant catalyst of cu — zn — al was wet crushed , and mixed with alumina sol to be made into slurry . subsequently there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst d - 4 having a chemical composition expressed in terms of atomic ratio of cu / zn / b / al being 1 . 33 / 1 . 0 / 0 . 3 / 0 . 3 . gallium oxide ( ga 2 o 3 ) in an amount of 15 g was dispersed in 500 ml of ion - exchanged water , and the dispersion was adjusted to a temperature of 35 ° c . to the resultant dispersion were added under stirring , a solution of 4 . 17 g of palladium nitrate dihydrate which was dissolved in 500 ml of ion - exchanged water and adjusted to a temperature of 35 ° c ., and 35 ml of 1 n aqueous solution of potassium hydroxide under stirring for 1 hour to prepare slurry . the resultant slurry was filtered to form a cake , which was washed with 4 liter of ion - exchanged water . thereafter the washed cake was dried and then calcined to obtain a catalyst of pd — ga . the resultant catalyst of pd — ga was wet crushed , and mixed with alumina sol to be made into slurry . subsequently , there were repeated the steps of immersing a cordierite - made honeycomb ( 400 cells / square inch ) into the slurried catalyst , blowing off an excess amount , and drying so that the catalyst was supported thereon in a catalyst amount of 200 g / l on a dry base . it was designated as catalyst e - 4 having a chemical composition expressed in terms of atomic ratio of pd / ga being 0 . 1 / 1 . 0 . a catalyst was prepared in the same manner as in the catalyst h - 1 , and designated as catalyst f - 4 . the catalyst a - 4 was packed as a catalyst bed in a through flow system reactor . prior to activity evaluation , a reduction treatment thereof was carried out by introducing into an evaporator , an aqueous solution of methanol having a water / methanol ratio of 1 . 5 at 200 ° c . and an lhsv of methanol of 15 hr − 1 . thereafter air was mixed in the evaporated water / methanol on the downstream side of the evaporator outlet , and the temperature in the introduction line leading to a catalyst bed was regulated so that the mixed water / methanol was charged in the catalyst bed at 200 ° c . the reaction was controlled so that the temperature at the inlet of the catalyst bed came to be 400 ° c . by the air rate . the chemical composition of the gas after the reaction was analyzed by means of gas chromatography . the reactivity of methanol is given in table 13 , and carbon monoxide concentration at the outlet of the catalyst bed is given in table 14 . the procedure in example 13 was repeated to carry out the reduction treatment and reaction of methanol except that the catalyst b - 4 was packed in the reactor . the results are given in table 13 and table 14 . the procedure in example 13 was repeated to carry out the reduction treatment and reaction of methanol except that the catalyst c - 4 was packed in the reactor , and an lhsv of methanol was set on 57 hr − 1 . the results are given in table 13 and table 14 . the procedure in example 13 was repeated to carry out the reduction treatment and reaction of methanol except that any of the catalysts d - 4 , e - 4 and f - 4 was packed in the reactor . the results are given in table 13 and table 14 .