Mechanisms of Copper-Based Catalyst Deactivation during CO₂ Reduction to Methanol

Abstract

Despite the fact that the methanol synthesis process includes industrially some of the most important catalytic chemical reactions, it is still not clear how different gaseous species impact catalyst component structure. With the goal to reduce CO2 emissions through hydrogenation to CH3OH, a higher H2O formation rate than in the production from compressed CO-rich feed should also be considered. It is known that steam accelerates the sintering of metals, several oxide compounds, and their interfaces. To determine the effect of moisture on the Cu/ZnO/Al2O3 catalysts, a commercial catalytic material was systematically aged at various gas compositions and analyzed using transient H2 surface adsorption, N2O pulse efficient chemisorption, X-ray photoelectron spectroscopy, scanning transmission electron microscopy mapping, X-ray powder diffraction, and N2 physisorption, and the mechanisms of deactivation were observed. A strong consistent relation between the compacting of Al2O3, the amount of water in the controlled streamflow, and the activity was found. This connected loss of support resulted in the (re)­forming of Cu, ZnO, and Cu/ZnO phases. Copper particle growth was modeled by applying a physical coalescence model. In the presence of CO and/or CH3OH, zinc oxide material started to cover the Cu granules, while H2O promoted the development of separate Cu regions.

Effects of Supercritical CO2 Treatment Temperatures on Mineral Composition, Pore Structure and Functional Groups of Shale: Implications for CO2 Sequestration

“…Quantification phase analysis was conducted with the value K method, following the Chinese oil and gas industry standard SY/T 5163-2018 [38][39][40], in which the relative deviation of test results is less than 10%, when mineral content is more than 40%. When the mineral standard and corundum are formulated into a two-phase mixture in a ratio of 1:1 by mass, the reference strength of the mineral i can be calculated as Equation (1). Therefore, the percentage of the mineral i can be described by Equation (2).…”

Improving the Cu/ZnO-Based Catalysts for Carbon Dioxide Hydrogenation to Methanol, and the Use of Methanol As a Renewable Energy Storage Media

“…The later pathway, which is slow and approaches the steady-state, is caused by the surface coverage of some reaction products and intermediates, especially water, and carbonated species (Roberts et al, 1993). It was found that the cause of catalyst deactivation was sintering of both Al 2 O 3 and Cu with water due to the decreasing Al 2 O 3 surface, and Cu particle size with increasing content of H 2 O (Prasňikar et al, 2019).…”

“…The Cu particle growth was fitted to a coalescence model for sintering (Figure 8B), which confirms coalescence as the operating mechanism. The increased particle migration is due to weak contact between the metal and support or increased surface diffusion of catalytic material (Prasňikar et al, 2019). The structures of ZnO and Al 2 O 3 species and metallic Cu can be stabilized to improve the catalyst lifetime, which can be accomplished by forming stable Cu interface with support material, and by stabilizing the dynamic nature of ZnO under working conditions using hydrophobic or hydrothermally stable materials.…”

“…The water generated in the RWGS during CO 2 reduction to methanol deactivates the catalyst, causing speciation of Cu active phase and phase separation (Kung, 1992;Liang et al, 2019;Prasňikar et al, 2019). Sahibzada et al observed a lower rate of methanol production in the presence of water in the H 2 /CO 2 feed (Sahibzada et al, 1998).…”

Flame Synthesis of Cu/ZnO–CeO2 Catalysts: Synergistic Metal–Support Interactions Promote CH3OH Selectivity in CO2 Hydrogenation

“… 8 The formation of a large amount of water byproduct during CO 2 hydrogenation in comparison to synthesis gas hydrogenation poses another challenge to catalyst stability, as water can accelerate the deactivation of Cu/ZnO/Al 2 O 3 catalysts. 9 − 12 …”