Catalytic methanation increasing yields

With these examples, the notion of sonochemical switching was introduced, which means that for the first time it was evidenced that the interaction of ultrasound with a reactive system is able to change the nature of the reaction products, not only to increase a rate or a yield. An application of this reaction was mentioned in a patent. It seems that a change in the mechanisms was not examined. The observation that electron acceptors such as nitroaromatics in catalytic amounts increase the yield of cyanide at the expense of the diphenyl-methane product was not exploited in this respect. The simultaneous occurrence of the destruction of acidic catalytic sites and the enhancement of a non-polar mechanism would constitute an interesting general interpretation. 

Effects of Li content on the catalytic behaviors and structures of LiNiLaOx catalysts The dpendence of performance of LiNiLaOx catalysts on Li content at 1073K was shown in Fig.l. When D/Ni mole ratio was 0, the relatively acidic LaNiOx had the highest CH4 conversion(92.0%), but no C2 yielded. The products were CO, CO2 and H2, and CO selectivity was 98.3%. It is not an OCM catalyst but a good catalyst for partial oxidation of methane(POM). With Li content and the baric property of LiNiLaOx catalysts increasing, CH4 conversion and CO selectivity decreased, but there was still no C2 formed imtil Li/Ni mole ratio was 0.4. There was a tumpoint of catalytic behavior between 0.2 and 0.4 (Li/Ni mole... 

The results obtained can be explained by considering the reactions involved in the processes. We can assume that the main reactions in catalytic pyrolysis are catalytic cracking of tars and light hydrocarbons, which will explain the increase in gas yields when the catalyst is present in the reaction bed (18). Steam reforming of tars (reac. 1), methane (reac. 2) and Cj (reac. 3), and the water-gas shift reaction (reac. 4) can explain the final gas composition generated in catalytic steam gasification. 

Hydrogenation of C02 occurs on a number of solid catalysts with Cu0/Zn0/Al203, methanol can be prepared but the equilibrium yields are less than 40%. The use of hybrid catalysts, containing solid acids, improves the yields by partial dehydration of the methanol to dimethyl ether.56 In situ IR spectroscopy has been used to identify catalytic intermediates in some processes. With Cu/ZrO/Si02, surface bound formate, gem-diolate and methoxide species could be observed before the final hydrolysis to methanol.57 Lithium salt-promoted Rh/Si02 catalysts increased the ethanol content of reduction mixtures from C02 as compared to the unpromoted reactions, but the main product was methane.58... 

The catalytic performance and the effect of coke deposition on the activity and selectivity, were found to be strongly dependent on the preparation procedure, on the reduction temperature, and on the type of support. At low reduction temperatures, the deposition of coke on Ni-Al, (Ni-Al-Ti)sg, and Ni-Ti samples decreased the selectivity to ethylene whereas on (Ni-Al-Ti)imp, deposition of coke increased selectivity. At high reduction temperatures, with only the exception of the Ni-Ti catalyst, coke deposition increased the selectivity to the desired product. The pattern of deactivation by coke was also different for the different samples. In Ni-Ti and (Ni-Al-Ti)sg samples, coke formation strongly diminished their activity and simultaneously increased methane production. With Ni-Al and (Ni-Al-Ti)imp samples, coke did not cause an significant deactivation or an increase in methane yield. Finally, catalysts... 

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