The carbonylation of methyl nitrite (MN) to synthesize dimethyl carbonate (DMC) is a promising route, but the lack of efficient and stable catalysts remains a major challenge for large-scale applications. In this study, by adjusting the alkalinity of the initial gel, NaY zeolites with tunable acidity were synthesized, and the amount of Lewis acid sites was optimized. Appropriate amounts of Lewis acid sites facilitated the interaction between NaY zeolites and Pd species, which was beneficial for stabilizing the oxidation state of Pd and promoting CO adsorption and activation, thereby contributing to the formation of the key intermediate *COOCH3. The catalyst PdCu/NaY-1 (alkalinity in the initial gel Na2O = 9) exhibited significant improvement in catalytic performance for the synthesis of DMC, with the WTYDMC of 1604 g·kgcat-1·h-1, the conversion of CO to DMC (CCO) of 88.7%, and the DMC selectivity based on CO (SDMC/CO) up to 100%.
Bin Wang,Tie-yan Chang,Zhao Jiang,Jin-jia Wei,Tao Fang
The unsatisfactory performance with high precious metal dosage of dehydrogenation catalysts has been the bottleneck for the development of liquid organic hydrogen carrier (LOHC). The most representative dodecahydro- N -ethylcarbazole in LOHC also faces the same problem. Here, we report a series of bimetallic PdCu catalysts with different ratios supported on reduced graphene oxide prepared by a facile one-pot synthesis method. The most cost-effective Pd 1.2 Cu/rGO catalyst with the lowest amount of precious metals in the catalysts reported for dehydrogenation of dodecahydro- N -ethylcarbazole was selected from a series of samples, while maintaining the catalytic activity and selectivity to the final product of N-ethylcarbazole as the Pd/rGO catalyst with the highest activity in recently reported studies. At the same time, the change of Pd and Cu content and the effect of preparation temperature on dehydrogenation performance were also studied, and the corresponding reaction kinetics were revealed. In combination with various characterization methods of catalyst, the relationship between structure and properties of PdCu NPs was explored in depth. The average particle size and electron transfer between Pd and Cu were identified as the key factors affecting the catalytic activity.
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