Effect of K Addition and Acidification of Zeolite Support on the Performance of Zr:Mo/Hzsm-5 Modified Catalyst in Methane Aromatization
The conversion of methane into higher hydrocarbons and aromatics on potassium doped modified zeolite Zr:Mo catalysts under non oxidizing conditions have been studied in a fixed bed catalytic reactor system at 450 0 C and at atmospheric pressure. The potassium addition reduces the formation of carbon during the catalytic reaction. This also results in the stability of the catalyst system and increased aromatics production. This is due to electronically modified active sites and increase in Bronsted acidity.
Pt Loaded HIGH-Ga Silicates for Aromatization of Light Paraffins and Methane
High Ga-contained pentasil type Ga-silicates having Si/Ga atomic ratios 20, 15, and 10 were synthesized by adopting the rapid crystallization method. The conversion rate of ethane was lower than that of propane, however since the selectivity to aromatics increased very much on the Pt/H-Ga-silicate, which involved Ga as Si/Ga ratio 15, the space-time yield of aromatics from ethane was rather higher than that from propane. Addition of O2 or H2 in the feed gas for ethane conversion retarded the reaction, indicating that the balance of dehydrogenation and hydrogenation activities is necessary to advance the aromatization. Although the conversion was very low, methane to aromatic conversion was observed on this catalyst.
The function of Cu(II) ions in the Mo/CuH-ZSM-5 catalyst for methane conversion under non-oxidative condition
Non-oxidative aromatization of methane was carried out over Mo/CuH-ZSM-5 and compared with that over Mo/H-ZSM-5. Cu(II) ions act as promoter in this reaction and improve the activity of the Mo/H-ZSM-5 catalyst notably. The effect of Cu species on the chemical state of Mo species and the changes of Cu species itself after reaction were studied by ESR and XPS methods. The introduction of Cu ions by ion-exchange method altered the reduction of Mo species, suppressed the dealumination of ZSM-5 framework and decreased coke formation over the catalyst. The results showed improved catalytic performance of Mo/H-ZSM-5 catalyst. The amount and nature of the coke which were influenced by the introduction of Cu ions were also investigated.