Catalytic hydrogenation of CO 2 to methanol is an exciting avenue to curb the rising CO 2 emissions and generate renewable energy or value-added products.Methanol synthesis via the thermal catalysis route gets increasing emphasis due to its fast kinetics and flexible combination of active components. In the last decade, many studies on CO 2 hydrogenation to methanol have been reported with different kinds of catalysts that have been synthesized and characterized using state-of-the-art surface science tools and techniques. In situ analysis techniques as well as theoretical (eg, density functional theory, Monte Carlo simulations, and Micro-Kinetics modeling) studies have been performed to understand the insights of morphology changes, the interaction of active sites, and the formation of intermediate species under the reaction conditions. In the present review, the advancements on CO 2 to methanol via hydrogenation route have been presented taking into consideration different perspectives spanning across thermodynamic aspects, the influence of reaction temperature, pressure, feed composition, space-velocity, and morphologically tuned novel catalyst on CO 2 conversion and methanol selectivity. Among the reported catalysts, the Al 2 O 3 -supported Cu-Zn catalyst showed better performance with 25% CO 2 conversion and 73% methanol selectivity at 170 C and 50 bar pressure. The CeO 2 -supported Pd-Zn catalyst showed 14% CO 2 conversion and 97% methanol selectivity at 220 C under 20 bar pressure. Also, CeO 2nanorods supported Cu-Ni catalyst showed good performance at 260 C and 30 bars, with around 18% CO 2 conversion and 73% methanol selectivity. Addi-

The most inspiring opportunity to reduce greenhouse gas emissions is direct hydrogenation of CO2 into a commodity of products, which is also an appealing choice for generating renewable energy. CO2 hydrogenation can yield methanol which has a broad range of applications. In the present study, a thermodynamic feasibility analysis of the CO2 hydrogenation reaction is carried out using the Aspen Plus tool. CO2 hydrogenation to methanol, reverse-water-gas-shift (RWGS), and methanol decomposition reactions were considered in this analysis. The effect of different parameters such as temperature (ranging from 50 to 500°C), pressures (ranging from 1 bar to 50 bar), and CO2:H2 molar ratio (ranging from 1:3 to 1:20) on methanol yield has been investigated. The Aspen predicted data is compared with the fixed-bed reactor experimental data. High pressure and low-temperature conditions are found to be the favourable option for a higher value of methanol yield. The CO2 conversion and CH3OH selectivity are favourable when the H2/CO2 molar ratio is greater than 3. A substantial gap between the Aspen predicted equilibrium conversion of CO2 and the experimental value of CO2 conversion is observed in the study.

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