Preparation of Active Cu/ZnO-based Catalysts for Methanol Synthesis

Abstract

In recent years, methanol has attracted much attention since it can be cleanly manufactured by the combined use of atmospheric CO2 recycling and water splitting via renewable energy. For the concept of "methanol economy", an active methanol synthesis catalyst should be prepared in a sophisticated manner rather than by empirical optimization approach. Even though Cu/ZnO-based catalysts prepared by coprecipitation are well known and have been extensively investigated even for a century, fundamental understanding on the precipitation chemistry and catalyst nanostructure has recently been achieved due to complexity of the necessary preparation steps such as precipitation, ageing, filtering, washing, drying, calcination and reduction. Herein we review the recent reports regarding the effects of various synthesis variables in each step on the physicochemical properties of materials in precursor, calcined and reduced states. The relationship between these characteristics and the catalytic performance will also be discussed because many variables in each step strongly influence the final catalytic activity, called "chemical memory". All discussion focuses on how to prepare a highly active Cu/ZnO-based catalyst for methanol synthesis. Furthermore, the preparation strategy we deliver here would be utilized for designing other coprecipitation-derived supported metal or metal oxide catalysts.

Controlling the Interfacial Charge Polarization of MOF-Derived 0D–2D vdW Architectures as a Unique Strategy for Bifunctional Oxygen Electrocatalysis

“…Remarkably, the particle size of ZrO 2 NPs decreased after incorporating different dopants (B, N, and B/N) into the graphitic carbon framework, which creates more structural defects in the carbon framework, thus lowering the particle size of ZrO 2 NPs during the carbonization process. The ZrO 2 NPs in the C/ZrO 2 nanohybrid showed a particle size of ∼15–20 nm, whereas the particle size of ZrO 2 NPs decreased to ∼2–3 nm in the BCN/ZrO 2 nanohybrid . It is well documented that the electrocatalytic processes over a metal catalyst are size-dependent.…”

“…Then, the morphological analysis of the as-synthesized nanohybrids was deeply investigated using transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) techniques. It was found that the UiO-66 MOF has octahedral 38 It is well documented that the electrocatalytic processes over a metal catalyst are size-dependent. Hence, the smallest nanosized BCN/ZrO 2 hybrid among others can provide lots of accessible active sites, yielding higher electrocatalytic rates.…”

Theoretical study on copper adsorption on ZnO surfaces for CO2 hydrogenation to methanol

“…In the case of the most stable system of Cu/ZnO(0001) (Zn-terminated) system, the Second, the charge transfer makes the Zn atom more negatively charged, which makes it more stable. This may help prevent Zn atoms from reacting with CO2 or H2 molecules [47].…”

Effect of Water Layer in a Microreactor on the Low-Temperature Synthesis of High-Activity Cu/ZnO Catalysts

“…During the aging process, uniform precipitates will transform into zincian malachite with high Zn incorporation, forming the porous structure of the catalysts. , Highly dispersed Cu–Zn mixed oxides are obtained after further calcination from precursors and ultimately reduced to active Cu/ZnO catalysts, while formation of the Cu–Zn interface at this stage is verified . High performance of the catalysts originating from the increasing Cu–Zn interfaces is reported in literatures. − Numerous studies have investigated the effect of aging − and calcination processes − on final activities of the catalysts; however, studies on the precipitation process are rarely concerned. Given that the structural evolution of Cu/ZnO catalysts originates from initial precipitates , and special “chemical memory” phenomenon was early proved during the process for preparing Cu/ZnO catalysts, namely, the sensibility of reaction characteristics to reaction conditions including changes of temperatures, solution concentrations, and pH values, − research works on the precipitation process are thus deemed very important.…”