CO2 Hydrogenation to Methanol with Ga- and Zn-Doped Mesoporous Cu/SiO2 Catalysts Prepared by the Aerosol-Assisted Sol-Gel Process*

Refining Surface Copper Species on Cu/SiO2 Catalysts to Boost Furfural Hydrogenation to Furfuryl Alcohol

Controllable hydrogenation of carbonyl groups (C=O) is crucial for converting furfural into high-value furfuryl alcohol. Instead of traditional impregnation method, a novel Cu-based catalyst (Cu/SiO2) is prepared using the ammonia evaporation method (AE) for the efficient hydrogenation of furfural to furfuryl alcohol under mild conditions. At the reaction conditions of 90 °C and 1 MPa H2, the 5Cu/SiO2-AE sample showed optimal performance with higher turnover frequency (36.0 h-1) and furfuryl alcohol selectivity (>99.9%). After five cycles, the catalyst recycled still showed a high reaction activity and selectivity for furfuryl alcohol. Characterization results such as XRD, H2-TPR, FT-IR, and XPS showed that the excellent catalytic performance of 5Cu/SiO2-AE catalyst was attributed to the formation of layered copper silicate and the high dispersion of Cu species. Furthermore, the formation of layered copper silicate resulted in a higher ratio of Cu+/(Cu0+Cu+) at a reduction temperature of 250 °C, which was also responsible for the optimum activity. This work showed the importance of controllable synthesis of layered copper silicate in improving the catalytic performance of copper-containing catalyst.

Multifunctional, Hybrid Materials Design via Spray-Drying: Much more than Just Drying

Spray-drying is a popular and well-known "drying tool" for engineers. This perspective highlights that, beyond this application, spray-drying is a very interesting and powerful tool for materials chemists to enable the design of multifunctional and hybrid materials. Upon spray-drying, the confined space of a liquid droplet is narrowed down, and its ingredients are forced together upon "falling dry." As  detailed in this article, this enables the following material formation strategies either individually or even in combination: nanoparticles and/or molecules can be assembled; precipitation reactions as well as chemical syntheses can be performed; and templated materials can be designed. Beyond this, fragile moieties can be processed, or "precursor materials" be prepared. Post-treatment of spray-dried objects eventually enables the next level in the design of complex materials. Using spray-drying to design (particulate) materials comes with many advantages-but also with many challenges-all of which are outlined here. It is believed that multifunctional, hybrid materials, made via spray-drying, enable very unique property combinations that are particularly highly promising in myriad applications-of which catalysis, diagnostics, purification, storage, and information are highlighted.

Catalytic Hydrogenation of CO2 to Methanol: A Review

High-efficiency utilization of CO2 facilitates the reduction of CO2 concentration in the global atmosphere and hence the alleviation of the greenhouse effect. The catalytic hydrogenation of CO2 to produce value-added chemicals exhibits attractive prospects by potentially building energy recycling loops. Particularly, methanol is one of the practically important objective products, and the catalytic hydrogenation of CO2 to synthesize methanol has been extensively studied. In this review, we focus on some basic concepts on CO2 activation, the recent research advances in the catalytic hydrogenation of CO2 to methanol, the development of high-performance catalysts, and microscopic insight into the reaction mechanisms. Finally, some thinking on the present research and possible future trend is presented.