Engineered Chemical Utilization of CO₂ to Methanol via Direct and Indirect Hydrogenation Pathways: A Review

Abstract

Nowadays, more than 80% of the world’s energy supply is provided by nonrenewable fossil fuels (oil, coal, and natural gas), which are the main sources of CO2 emission. The conversion of CO2 into the most useful organic chemicals (methanol and ethylene glycol (EG)) not only effectively mitigates CO2 emissions but also produces value-added chemicals and replaces nonrenewable energy sources. This Review provides a comprehensive view of the significant research progress on indirect CO2 hydrogenation to methanol and EG through the ethylene carbonate intermediate. First, the advances and challenges of direct catalytic hydrogenation of CO2 to methanol are addressed. Subsequently, the advances in CO2 epoxidation to cyclic carbonates, particularly to ethylene carbonate, are summarized. This matured and commercialized ethylene carbonate (EC) production route is vital because of the efficient production of EG and methanol from catalytic hydrogenation of EC and hydrolysis of EC to EG, which replaces the conventional EG production process by hydration of ethylene oxide. Then, the progress on the catalytic hydrogenation of CO2-derived EC is discussed in detail, focusing on Cu-based heterogeneous catalysts. We provided a detailed discussion with emphasis on the nature, evolution, and precise role of active sites in Cu-based catalysts, including other influencing factors such as the preparation method, support, and addition of promoters. Moreover, the possible hydrogenation reaction mechanism, reaction conditions, design optimization, and on-site assessment of Cu-based catalysts for EC hydrogenation are included. Lastly, we provided a summary and outlook.

Feasibility, Limit, and Suitable Reaction Conditions for the Production of Alcohols and Hydrocarbons from CO and CO2 through Hydrogenation, a Thermodynamic Consideration

“…The above results clearly demonstrate that the RWGS reaction does have a severe impact on the CO 2 hydrogenation to alcohols and hydrocarbons. An ideal solution to this problem is naturally to design a catalyst that is only active to CO 2 hydrogenation to the defined products but inactive to the RWGS reaction. ,, This is however rather difficult. An alternative measure is adding an appropriate amount of CO in the CO 2 + H 2 feed to resist the RWGS reaction during the CO 2 hydrogenation to alcohols and hydrocarbons.…”

“…Meanwhile, with the increasingly loud voice of abating CO 2 emission to achieve a carbon emission peak and carbon neutrality against time, the conversion of CO 2 into valuable liquid fuels and value-added chemicals, with the help of “green H 2 ” from the renewable energy, is also considered as a potential measure in the exploitation of renewable resources and the remission of greenhouse gases to counteract the present serious threat of global warning. ,− Although the hydrogenation of CO 2 can be translated into the conversion of syngas by converting CO 2 to syngas in advance via the reverse water gas shift (RWGS) reaction, the direct hydrogenation of CO 2 to alcohols and hydrocarbons is deemed to be more efficient and cost-effective. Traditionally, the RWGS or water gas shift (WGS) reaction can be used to adjust the H 2 /CO ratio in syngas or produce hydrogen from fuel reforming.…”

Enhanced Surface Charge Localization Over Nitrogen-Doped In2O3 for CO2 Hydrogenation to Methanol with Improved Stability

“…Among the various options considered, CO 2 hydrogenation to methanol is promising because methanol can be used as a transportation fuel or as an intermediate for chemical syntheses. , A copper-based catalyst was first employed for CO 2 hydrogenation to methanol because of its application in industrialized methanol production from CO hydrogenation. − Significant efforts are being made to improve the activity and stability of copper-based catalysts . However, at the same time, non-copper-based catalysts of high activity and methanol selectivity for CO 2 hydrogenation have been actively pursued. − In 2012 and 2013, , our group predicted, via density functional theory (DFT) calculations, that In 2 O 3 has great potential for selective hydrogenation of CO 2 to methanol. The surface oxygen vacancy of In 2 O 3 plays an important role in the activation and hydrogenation of CO 2 .…”

Boosting Conversion of CO2 to Light Olefins over MgO-Promoted ZnZrO/SAPO-34 Bifunctional Catalyst

“…The rapid consumption of fossil fuels by industry has resulted in a large quantity of CO 2 that is being released into the atmosphere, which has caused a significant global ecological imbalance, as a result of the greenhouse effect. − In order to solve the global environmental problems, the carbon neutrality goal was proposed by the Intergovernmental Panel on Climate Change and has become an important goal to solve global environmental problems. In order to achieve carbon neutrality, convert CO 2 into valuable chemicals, actualize the resource utilization of carbon dioxide and the storage of clean energy, which has caused extensive research. − Light olefins (C 2 = –C 4 = ) are extremely important chemical materials, since they serve not only as biofuels but also as high value-added chemical precursors for products such as lubricants, polymers, and detergents. − Therefore, the technique for converting CO 2 into light olefins has attracted extensive attention worldwide.…”