The emerging process of CO2 hydrogenation through heterogenous catalysis into important bulk chemicals provides an alternative strategy for sustainable and low-cost production of valuable chemicals, and brings an important chance for mitigating CO2 emissions. Direct synthesis of the family of unsaturated heavy hydrocarbons such as α-olefins and aromatics via CO2 hydrogenation is more attractive and challenging than the production of short-chain products to modern society, suffering from the difficult control between C-O activation and C-C coupling towards long-chain hydrocarbons. In the past several years, rapid progress has been achieved in the development of efficient catalysts for the process and understanding of their catalytic mechanisms. In this review, we provide a comprehensive, authoritative and critical overview of the substantial progress in the synthesis of α-olefins and aromatics from CO2 hydrogenation via direct and indirect routes. The rational fabrication and design of catalysts, proximity effects of multi-active sites, stability and deactivation of catalysts, reaction mechanisms and reactor design are systematically discussed. Finally, current challenges and potential applications in the development of advanced catalysts, as well as opportunities of next-generation CO2 hydrogenation techniques for carbon neutrality in future are proposed.

Towards the development of the emerging process of CO2 heterogenous hydrogenation into high-value unsaturated heavy hydrocarbons

The alarming scenario of global warming continues to drive mitigation actions to reduce the global temperature rise and keep this earth a dwelling place. In this regard, all the countries in this world have agreed upon a common agenda to take appropriate actions to reduce CO2 emission, mainly from the extensive use of fossil resources to meet the energy demand. In the past decade, an immense amount of work has been done in this regard, focusing on CO2 sequestration and CO2 utilization to valuable end products i.e. methanol, DME, formic acid, lower olefins, etc. A combination of both may not only utilize alternative carbon sources compared to the fossil sources but also imposes a carbon-neutral pathway, thereby aiding the reduction of CO2 accumulation in the atmosphere. CO2 transformation to lower olefins (C2-C4=) has the utmost demand to have an alternative environmental-friendly raw material for the polymer industries, but the majority of catalysts sought for this process are suffering from low selectivity (must possess low CH4, CO, and higher hydrocarbons, paraffin, and aromatic selectivity), which has driven increased interest in the design of an efficient hydrogenation catalyst. A detailed understanding of the structural-property relationships is vital towards designing scalable, efficient, economical, and intrinsically stable catalysts for the process. Therefore, this review focuses on the advances in heterogeneous catalyst design for CO2 hydrogenation to lower olefins, focusing on structure-property correlation via various influencing parameters, describing modified Fischer-Tropsch pathway and methanol mediated pathway with the influence of different types of zeolite and tandem catalysts. Also, mechanisms over these catalysts are discussed. Finally, future research strategies are proposed that would guide the design of novel CO2 hydrogenation catalysts incorporating a combination of core-shell tandem technology, machine learning, advanced DFT, and spectroscopic (in situ, ex situ) understanding of the reaction mechanism.

A review on CO2 hydrogenation to lower olefins: Understanding the structure-property relationships in heterogeneous catalytic systems

The use of anthropogenic CO2 as a carbon source for the synthesis of value-added chemicals, mainly light olefins, is a green route that has not been extensively explored. Designing robust catalysts...

Chongyang Wei

Papers

The evolutions of carbon and iron species modified by Na and their tuning effect on the hydrogenation of CO2 to olefins

Insights into the regulation of FeNa catalysts modified by Mn promoter and their tuning effect on the hydrogenation of CO2 to light olefins