No abstract

The efficient conversion of CO 2 to useful chemicals is a promising way to reduce atmospheric CO 2 concentration and also reduce reliance on fossil-based resources. Although much progress has been made toward the production of basic chemicals, like methanol, through CO 2 hydrogenation, the direct conversion of CO 2 to valueadded aromatics, especially p-xylene (PX), is still a great challenge due to the inert nature of CO 2 and high barrier for C−C coupling. Herein, a bifunctional catalyst composed of Cr 2 O 3 and H-ZSM-5 zeolite (Cr 2 O 3 / H-ZSM-5) was designed for the direct conversion of CO 2 to aromatics. Due to the concertedly synergistic effect between the two components in this bifunctional catalyst, aromatics selectivity of ∼76% at CO 2 conversion of 34.5% was achieved, and there was no catalyst deactivation after 100 h of long-term stability testing. Moreover, a modified bifunctional catalyst Cr 2 O 3

Cu-based catalysts have attracted much interest in CO 2 hydrogenation to methanol because of their high activity. However, the effect of interface, coordination structure, particle size and other underlying factors existed in heterogeneous catalysts render to complex active sites on its surface, therefore it is di cult to study the real active sites for methanol synthesis. Here, we report a novel Cu-based catalyst with isolated Cu active sites (Cu 1 -O 3 units) for highly selective hydrogenating CO 2 to methanol at low temperature (100% selectivity for methanol at 180 o C). Experimental and theoretical results reveal that the single-atom Cu-Zr catalyst with Cu 1 -O 3 units is only contributed to synthesize methanol at 180 o C, but the Cu clusters or nanoparticles with Cu-Cu or Cu-O-Cu active sites will promote the process of reverse water gas shift (RWGS) side reaction to form undesirable byproducts CO. Furthermore, the Cu 1 -O 3 units with tetrahedral structure could gradually migrate to the catalyst surface for accelerating CO 2 hydrogenation reaction during catalytic process. The high activity isolated Cu-based catalyst with legible structure will be helpful to understand the real active sites of Cu-based catalysts for methanol synthesis from CO 2 hydrogenation, thereby guiding further design the Cu catalyst with high performance to meet the industrial demand, at the same time as extending the horizontal of single atom catalyst for application in the thermal catalytic process of CO 2 hydrogenation.

We presented a promising hybrid catalyst, named Cr/Zn–Zn/Z5@S1, to effectively realize the one-pass selective conversion of syngas to para-xylene.

The preparation of a Zn–Cr@SAPO capsule catalyst and the two different mass transfer routes over the capsule catalyst and physical mixture catalyst in light olefins synthesis from syngas.