A New Method of Low Temperature Methanol Synthesis

Hydrogenation of Carboxylic Acids, Esters, and Related Compounds over Heterogeneous Catalysts: A Step toward Sustainable and Carbon-Neutral Processes

The catalytic hydrogenation of esters and carboxylic acids represents a fundamental and important class of organic transformations, which is widely applied in energy, environmental, agricultural, and pharmaceutical industries. Due to the low reactivity of the carbonyl group in carboxylic acids and esters, this type of reaction is, however, rather challenging. Hence, specifically active catalysts are required to achieve a satisfactory yield. Nevertheless, in recent years, remarkable progress has been made on the development of catalysts for this type of reaction, especially heterogeneous catalysts, which are generally dominating in industry. Here in this review, we discuss the recent breakthroughs as well as milestone achievements for the hydrogenation of industrially important carboxylic acids and esters utilizing heterogeneous catalysts. In addition, related catalytic hydrogenations that are considered of importance for the development of cleaner energy technologies and a circular chemical industry will be discussed in detail. Special attention is paid to the insights into the structure-activity relationship, which will help the readers to develop rational design strategies for the synthesis of more efficient heterogeneous catalysts.

Efficient and New Production Methods of Chemicals and Liquid Fuels by Carbon Monoxide Hydrogenation

Carbon monoxide (CO) hydrogenation is an important step for efficient utilization of carbon resources in C1 (one carbon) chemistry. Over recent years, this direction has been a hot research area in academia and industry and has also been one of the most challenging routes for the nonoil carbon resources utilization process. A large number of novel reaction routes and catalysts have been studied and reported. Efficient activation and directional conversion of CO are key aspects in the process of CO utilization. Furthermore, effectively activating C-O and C-C bond formation as well as controlling carbon chain growth is the current technical bottleneck of CO hydrogenation. This mini-review introduces the latest research progress for different catalyst systems and processes in CO hydrogenation and analyzes the factors that control the performance of catalysts in different reaction systems. Here, much focus is put on the synthesis of long-chain hydrocarbons, light olefins, C₂₊ oxygenates, and aromatics, essentially in comparison with the previous reports. Finally, the present challenges and future research directions have been discussed.

CO2 Hydrogenation to Methanol by a Liquid-Phase Process with Alcoholic Solvents: A Techno-Economic Analysis

Synthesis of methanol from recirculated CO2 and H2 produced by water electrolysis allows sustainable production of fuels and chemical storage of energy. Production of renewable methanol has, however, not achieved commercial breakthrough, and novel methods to improve economic feasibility are needed. One possibility is to alter the reaction route to methanol using catalytic alcoholic solvents, which makes the process possible at lower reaction temperatures. To estimate the techno-economic potential of this approach, the feasibilities of the conventional gas-phase process and an alternative liquid-phase process employing 2-butanol or 1-butanol solvents were compared by means of flowsheet modelling and economic analysis. As a result, it was found that despite improved methanol yield, the presence of solvent adds complexity to the process and increases separation costs due to the high volatility of the alcohols and formation of azeotropes. Hydrogen, produced from wind electricity, was the major cost in all processes. The higher cost of the present, non-optimized liquid-phase process is largely explained by the heat required in separation. If this heat could be provided by heat integration, the resulting production costs approach the costs of the gas-phase process. It is concluded that the novel reaction route provides promising possibilities, but new breakthroughs in process synthesis, integration, optimization, and catalysis are needed before the alcoholic solvent approach surpasses the traditional gas-phase process.

Formic acid-assisted synthesis of highly efficient Cu/ZnO catalysts: effect of HCOOH/Cu molar ratios

Metallic Cu/ZnO catalysts were directly prepared by a formic acid-assisted solid-state combustion method without further reduction.

Performance of Cu-Based Catalysts in Low-Temperature Methanol Synthesis

The reactions of the methanol synthesis were conducted from the CO/CO2/H2 on the Cu-based catalysts using different solvent at 443 K and 3.0 MPa. The alcohol solvent had the activity in the low-temperature methanol synthesis reaction. The activity of the Cu-based catalyst with ZnO as carrier was higher than that of the catalyst with CeO2, Al2O3, or TiO2 as carrier separately in the reaction. The addition of the CeO2 to the Cu/ZnO catalysts improved the copper species dispersion, so that it was easier for the reduction of the Cu/CeO2-ZnO catalyst than that of the Cu/ZnO catalyst according to the TPR analysis. The variation trend of the BET surface area and the copper surface area was consistent with those of the activity for the Cu/ZnO and the Cu/CeO2-ZnO catalysts in the reaction. The activity of the Cu/CeO2-ZnO catalyst was higher than that of the Cu/ZnO catalyst in the reaction.