Catalytic Conversion of Carbon Oxides in Confined Spaces: Status and Prospects

Abstract

Owing to the depletion of fossil reserves and the global warming by released greenhouse gas from the consumption of fossil resources, the catalytic conversion of carbon oxide (COx, including CO2 and CO) into fuels and high‐value chemicals has attracted tremendous interest in the field of catalysis. Developing high‐performance and practical catalysts with high activity, selectivity, and stability is of great importance but remains a huge challenge. A variety of new strategies were developed to take advantage of confinement effect to address the challenges that are relevant to the highly‐efficient transformation and utilization of COx by performing catalytic reactions in a confined space. The status on this issue can be divided into three aspects: improvement in catalytic activity, increase in catalytic selectivity and enhancement in catalytic stability. In this review, the progress in the field of promoted catalytic conversion of COx in confined spaces will be presented and discussed. Especially, the specific promoting mechanism in terms of the confinement effect for COx‐related transformations in confined spaces and the relationship between the impact of the confined space on the catalytic activity, selectivity, and stability regarding of COx conversions are highlighted. Finally, the future prospects on the opportunities and challenges of catalytic conversion of COx in confined spaces are outlined.

Transient behavior of CO and CO2 hydrogenation on Fe@SiO2 core-shell model catalysts – A stoichiometric analysis of experimental data

“…Carbon deposition and thus iron carbide formation during CO2 hydrogenation plays a minor role for Fe@SiO2 catalysts, as reported previously [35]. One may also speculate that a confinement effect of the core-shell arrangement is responsible for the high CO and low CH4 selectivity, which has been reported for syngas reactions in confined spaces in literature [61,62]. We assume that iron…”

Transient Behavior of CO and CO2 Hydrogenation on Fe@SiO2 Core–Shell Model Catalysts—A Stoichiometric Analysis of Experimental Data

“…Carbon deposition and thus iron carbide formation during CO2 hydrogenation plays a minor role for Fe@SiO2 catalysts, as reported previously [48]. One may also speculate that a confinement effect of the core-shell arrangement was responsible for the high CO and low CH4 selectivity, which has been reported for syngas reactions in confined spaces in the literature [71,72]. We assume that the iron oxide species were formed by the transformation of carbidic or metallic iron species in H2O-rich atmospheres within the confined core-shell structure during the hydrogenation of CO2-rich syngas.…”

Confined Catalysts Application in Environmental Catalysis: Current Research Progress and Future Prospects

“…Catalytic performance can be strongly influenced by regulating the mass transfer of catalysts, the adsorption and activation of reactants at active sites, and the desorption of products. [6] Among various types of heterogeneous catalysis, space-confined catalysis, which focuses on the space-confining effect during the catalytic reaction, has evolved into a feasible strategy for designing high-efficiency catalysts for various essential catalytic reactions; unique nanoscale chemical environments can be partitioned from the surrounding bulk space effectively via space-confined catalysis. [7] The confined effect in heterogeneous catalysis was first acknowledged by Derouane in the 1980 s [8] , and both reacting molecules and confined metal/metal-oxide nanoparticles (NPs) were recognized to be affected by confinement.…”

“…Heterogeneous catalysts consist of active sites and surrounding environments. Catalytic performance can be strongly influenced by regulating the mass transfer of catalysts, the adsorption and activation of reactants at active sites, and the desorption of products [6] . Among various types of heterogeneous catalysis, space‐confined catalysis, which focuses on the space‐confining effect during the catalytic reaction, has evolved into a feasible strategy for designing high‐efficiency catalysts for various essential catalytic reactions; unique nanoscale chemical environments can be partitioned from the surrounding bulk space effectively via space‐confined catalysis [7] .…”