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.

Propane nonoxidative dehydrogenation (PDH) is a promising route to produce propylene with the development of shale gas exploration technology. Co-based catalysts with low cost and low toxicity could activate C−H effectively, but they suffer from deactivation with coke formation. In this work, a catalyst formed by incorporating highly dispersed Co sites into a Silicalite-1 zeolite framework (Co-Silicalite-1) is synthesized by a hydrothermal protocol in the presence of ammonia, which exhibits superior propane dehydrogenation catalytic performance with 0.0946 mmol C 3 H 6 •s −1 • g Co −1 and propylene selectivity higher than 98.5%. It also shows outstanding catalytic stability and coking resistance in a 3560 min time-on-stream. Combined characterization results demonstrate that the tetrahedrally coordinated Co 2+ site serves as the PDH catalytic active site, which is stabilized by Si−O units of the zeolite framework. Incorporation of Co sites into the zeolite framework could avoid the reduction of Co species to metallic Co. Moreover, the catalytic performance is improved by the enhanced propane adsorption and propylene desorption.

No abstract

Antibiotic pollution is becoming an increasingly serious threat in different regions of China. The distribution of antibiotics in water sources varies significantly in time and space, corresponding to the amount of antibiotics used locally. The main source of this contamination in the aquatic environment is wastewater from antibiotic manufacturers, large scale animal farming, and hospitals. In response to the excessive antibiotic contamination in the water environment globally, environmentally friendly alternatives to antibiotics are being developed to reduce their use. Furthermore, researchers have developed various antibiotic treatment techniques for the degradation of antibiotics, such as physical adsorption, chemical oxidation, photodegradation, and biodegradation. Among them, biodegradation is receiving increasing attention because of its low cost, ease of operation, and lack of secondary pollution. Antibiotic degradation by enzymes could become the key strategy of management of antibiotics pollution in the environment in future. This review summarizes research on the distribution of antibiotics in China’s aquatic environments and different techniques for the degradation of antibiotics. Special attention is paid to their degradation by various enzymes. The adverse effects of the pollutants and need for more effective monitoring and mitigating pollution are also highlighted.