RESUMO
Ethylene glycol (EG), a useful chemical raw material, has been widely applied in many aspects of modern society. The conventional preparation of ethylene glycol mainly uses the petroleum route at high temperatures and pressure. More and more approaches have been developed to synthesize EG from CO2 and its derivatives under mild conditions. In this review, the ambient synthesis of EG from thermocatalysis, photocatalysis, and electrocatalysis is highlighted. The coal-to-ethylene glycol technology, one of the typical thermal catalysis routes for EG preparation, is relatively mature. However, it still faces some problems to be solved in industrialization. The recent progress in the development of coal-to-ethylene glycol technology is introduced. The main focus is on how to realize the preparation of EG under mild conditions. The strategies include doping promoters, modification of supports, design of catalysts with special structures, etc. Furthermore, the emerging technological progress of photocatalytic and electrocatalytic ethylene glycol synthesis under ambient conditions is introduced. Compared with the thermal catalytic reaction, the reaction conditions are milder. However, there are still many problems in large-scale production. Finally, we propose future development issues and related prospects for the ambient synthesis of EG using different catalytic routes.
RESUMO
The rapid economic and societal development have led to unprecedented energy demand and consumption resulting in the harmful emission of pollutants. Hence, the conversion of greenhouse gases into valuable chemicals and fuels has become an urgent challenge for the scientific community. In recent decades, perovskite-type mixed oxide-based catalysts have attracted significant attention as efficient CO2 conversion catalysts due to the characteristics of both reversible oxygen storage capacity and stable structure compared to traditional oxide-supported catalysts. In this review, we hand over a comprehensive overview of the research for CO2 conversion by these emerging perovskite-type mixed oxide-based catalysts. Three main CO2 conversions, namely reverse water gas shift reaction, CO2 methanation, and CO2 reforming of methane have been introduced over perovskite-type mixed oxide-based catalysts and their reaction mechanisms. Different approaches for promoting activity and resisting carbon deposition have also been discussed, involving increased oxygen vacancies, enhanced dispersion of active metal, and fine-tuning strong metal-support interactions. Finally, the current challenges are mooted, and we have proposed future research prospects in this field to inspire more sensational breakthroughs in the material and environment fields.
RESUMO
Oxidative coupling of toxic pollutant CO to form the platform raw chemical material dimethyl oxalate (DMO) has been industrialized however the catalytic mechanism has been unknown so far. The reaction mechanism of CO oxidative coupling to form DMO on a Pd(111) surface has been investigated using density functional theory (DFT) and in situ diffuse reflectance infrared (DRIR) spectroscopy. DFT calculations and in situ DRIRS measurements indicate that two co-adsorbed intermediates COOMe and OCCO, initiate the reaction. C-C coupling occurs earlier due to a low coupling barrier and small steric hindrance. The results also suggest that Pd(111) is selective towards DMO over DMC, and that CO pre-adsorption and CO in excess effectively enhance the yield of DMO. The microscopic elucidation of this important reaction suggests improvements in coal-to-EG (CTEG) production which can be applied in practice to effectively enhance the yield and reduce the cost. The results may help with further fine-tuning and designing of high-efficient noble metal catalysts.
