ABSTRACT
The variability of CO2 hydrogenation reaction demands new potential strategies to regulate the fine structure of the catalysts for optimizing the reaction pathways. Herein, we report a dual-site strategy to boost the catalytic efficiency of CO2-to-methanol conversion. A new descriptor, τ, was initially established for screening the promising candidates with low-temperature activation capability of CO2, and sequentially a high-performance catalyst was fabricated centred with oxophilic Mo single atoms, who was further decorated with Pt nanoparticles. In CO2 hydrogenation, the obtained dual-site catalysts possess a remarkably-improved methanol generation rate (0.27â mmol gcat. -1 h-1). For comparison, the singe-site Mo and Pt-based catalysts can only produce ethanol and formate acid at a relatively low reaction rate (0.11â mmol gcat. -1 h-1 for ethanol and 0.034â mmol gcat. -1 h-1 for formate acid), respectively. Mechanism studies indicate that the introduction of Pt species could create an active hydrogen-rich environment, leading to the alterations of the adsorption configuration and conversion pathways of the *OCH2 intermediates on Mo sites. As a result, the catalytic selectivity was successfully switched.
ABSTRACT
Understanding the synergism between the metal site and acid site is of great significance in boosting the efficiency of bi-functional catalysts in many heterogeneous reactions, particularly in biomass upgrading. Herein, a "confined auto-redox" strategy is reported to fix CeO2-anchored Pt atoms on the inner wall of a ZSM-5 cage, achieving the target of finely controlling the placements of the two active sites. Compared with the conventional surface-supported counterpart, the encapsulated Pt/CeO2@ZSM-5 catalyst possesses remarkably-improved activity and selectivity, which can convert >99% furfural into cyclopentanone with 97.2% selectivity in 6 h at 160 °C. Besides the excellent catalytic performance, the ordered metal-acid distribution also makes such kind of catalyst an ideal research subject for metal-acid interactions. The following mechanization investigation reveals that the enhancement is strongly related to the unique encapsulation structure, which promotes the migration of the reactants over different active sites, thereby contributing to the tandem reaction.
ABSTRACT
OBJECTIVE: This study was designed to analyze the clinical efficacy of ceftazidime combined with levofloxacin on heart failure complicated with pulmonary infection and its influence on cardiopulmonary function. METHODS: A total of 124 patients with heart failure and pulmonary infection admitted to our hospital from June 2018 to October 2019 were divided into groups according to different treatment schemes. Thereinto, 60 patients who were given ceftazidime intravenous drip on the basis of routine treatment were included in group A, and 64 who were given levofloxacin hydrochloride injection based on intravenous drip in group A were included in group B. The clinical efficacy, cardiac and lung function, pathogenic bacteria, infection, immune indexes and adverse reactions before and after treatment were compared. RESULTS: After treatment, the adjusted levels of LVEF, LVEDD and LA in group B after treatment were greater than those in group A (P<0.05); the levels of MMV, TLC and FEV1 in group B were increased more than those in group A (P<0.05). After treatment, the levels of BNP, PCT and CRP in groups A and B decreased compared with those before treatment (P<0.05). Furthermore, the down-regulated levels of BNP, PCT and CRP in group B were higher than those in group A after treatment (P<0.05). After treatment, the levels of serum CD3+, CD4+, CD4+/CD8+ in group B increased more and CD8+ decreased more. The clinical efficacy of group B after 7 days was higher than that of group A (P<0.01). Patients were followed up for one month, and there was no marked difference in their adverse drug reaction rates (P>0.05). CONCLUSION: To sum up, ceftazidime combined with levofloxacin on patients with heart failure and pulmonary infection can improve the immune function while optimizing the clinical efficacy and cardiopulmonary function.