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The preparation method and calcination temperature of metal-organic framework (MOFs)-derived materials are critical factors affecting catalytic performance. In this work, the preparation conditions of MOFS precursors were optimized, and zinc-based catalysts with different activities (MOF5-700, MOF5-750, and MOF5-800) were obtained by pyrolysis of MOFS precursors under nitrogen, which were then applied to an acetylene acetoxylation reaction system. According to the results, the conversion rate of acetic acid under catalysis was significantly different. (MOF5-700 (48%), MOF5-750 (62%), and MOF5-800 (22%)). Comparing the activity of the catalyst with the industrial catalyst Zn(OAc)2/AC (20%), MOF5-750 showed higher activity, and the acetic acid conversion rate remained around 60% after 50 h of stability testing. By characterization analysis, MOFs-derived materials were obtained after proper temperature pyrolysis. They have high mesoporous content, defects, and oxygen-containing functional groups and can maintain a good crystal structure, greatly reducing the loss of active components. This is the main reason for the good performance of the MOF5-750 catalyst in acetylene acetoxylation. Thus, the preparation conditions and favorable pyrolysis temperature of MOF derivative catalysts play a key role in the catalytic performance of acetylene acetoxylation. [ABSTRACT FROM AUTHOR]

The role of solvents is crucial in catalyst preparation. With regard to catalysts prepared with activated carbon (AC) as the carrier, when water is used as a solvent it is difficult for the solution to infiltrate the AC. Because AC comprises a large number of C atoms and is a nonpolar material, it is more effective for the adsorption of nonpolar substances. Since the water and active ingredients are polar, they cannot easily infiltrate AC. In this study, the dispersion of the active component was significantly improved by optimizing the solvent, and the particle size of the active component was reduced from 33.08 nm to 15.30 nm. The specific surface area of the catalyst is significantly increased, by 10%, reaching 991.49 m2/g. Under the same reaction conditions, the conversion of acetic acid by the catalyst prepared with the mixed solvent was maintained at approximately 65%, which was 22% higher than that obtained using the catalyst prepared with water as the solvent. [ABSTRACT FROM AUTHOR]

Herein, we report a multiple regulation strategy towards an all-in-one NiCuMo/MoOx heterostructure for the HOR, which exhibits ultrahigh HOR activity (j@0.05V = 4.63 mA cm−2) and excellent durability for almost 24 h for the synergistic regulation of Mo and Cu on the Ni electrode. This study provides a new strategy for designing efficient non-noble metal-based HOR catalysts. [ABSTRACT FROM AUTHOR]

• The influences of electronic metal-support interactions (EMSI) on the catalytic hydrogenation of ethylene over Pd n /CeO2 (n = 4, 7, 10) have been studied. • The charge redistribution on the Pd cluster creates 2 typical sites: IF sites located at the interface between metal and support and T sites located at the topmost of the cluster. • IF sites show extremely higher activity for H 2 dissociation and T sites show better activity for ethylene hydrogenation. • At high H coverage, both the kinetics and thermodynamics of the hydrogenation reaction would be significantly promoted. • The two types of sites should collaborate synergically to promote the hydrogenation process. The catalytic activity of supported catalyst is closely related to the electronic metal-support interactions (EMSI). In this paper, first principles density functional theory study was conducted to understand the EMSI between Pd clusters (Pd 4 , Pd 7 , Pd 10) and CeO 2 substrate. When Pd was loaded on CeO 2 surface, the electrons of Pd would transfer to the CeO 2 substrate via Pd-O bonding interactions. Moreover, the charge redistribution on the Pd cluster leads to significant polarization of electron density. Consequently, the Pd atoms located at the metal-support interface (IF site) are positively charged, while the Pd atoms at the topmost (T site) are negatively charged. The H 2 dissociation and ethylene hydrogenation at these sites were calculated with both low and high hydrogen coverage. It was found that the two types of sites should collaborate synergically to promote the hydrogenation of ethylene. In particular, the IF sites exhibit relatively high activity for H 2 dissociation, while the T sites show superior catalytic efficiency for ethylene hydrogenation. Therefore, the EMSI induced charge polarization can tune the electronic structure and charge state of supported metal catalysts, which further determines the performance of different region on the catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs)-derived materials with a large specific surface area and rich pore structures are favorable for catalytic performance. In this work, MOFs are successfully prepared. Through pyrolysis of MOFs under nitrogen gas, zinc-based catalysts with different active sites for acetylene acetoxylation are obtained. The influence of the oxygen atom, nitrogen atom, and coexistence of oxygen and nitrogen atoms on the structure and catalytic performance of MOFs-derived catalysts was investigated. According to the results, the catalysts with different catalytic activity are Zn-O-C (33%), Zn-O/N-C (27%), and Zn-N-C (12%). From the measurements of X-ray photoelectron spectroscopy (XPS), it can be confirmed that the formation of different active sites affects the electron cloud density of zinc. The electron cloud density of zinc affects the ability to attract CH3COOH, which makes catalysts different in terms of catalytic activity. [ABSTRACT FROM AUTHOR]

Zinc acetate (Zn(OAc)2) loaded on activated carbon (AC) is the most commonly used catalyst for the industrial synthesis of vinyl acetate (VAc) using the acetylene method. The aim of this study is to optimize the Zn(OAc)2/AC catalyst by adding co-catalysts to improve its activity and stability. Ternary catalysts were synthesized by adding Co and Ni to the Zn(OAc)2/AC catalyst (Zn-Co-Ni/AC). Due to the strong synergistic effect among promoter Co, Ni, and the active component of Zn(OAc)2, the resulting catalyst is capable to absorb more acetic acid and less acetylene. The stability and activity of Zn-Co-Ni/AC catalyst have been improved through electron transfer to alter the electron cloud density around the Zn element. Under the same reaction conditions, the activity of Zn-Co-Ni/AC catalyst was enhanced by 83% compared to that of Zn(OAc)2/AC, and the activity was still as high as 30.1% after 120 h of testing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Monolithic high-entropy perovskite oxide was innovatively proposed to activate PMS. • Entropy-stabilized structure could significantly suppress the cobalt leaching. • Multimetallic composition led to a boosted catalytic activity (TOF: 15.38 min−1). • The monolithic catalyst was easily recyclable and allowed rapid mass transfer. • The monolithic catalyst showed high efficacy and good durability in MNZ removal. Utilizing cobalt-containing oxides as catalysts is one of the most popular ways of activating peroxymonosulfate (PMS) to generate sulfate radical (SO 4 −) for elimination of organic pollutants. However, it still remains a great challenge to realize high activity, good stability, and easy recyclability at the same time. Herein, we demonstrate that high-entropy perovskite oxide (HEPO) washcoated porous alumina ceramic (La(Co 0.2 Al 0.2 Fe 0.2 Mn 0.2 Cu 0.2)O 3 @PAC) is a superb catalyst for PMS activation. In particular, benefiting from unique multimetallic composition and entropy-stabilized structure, the La(Co 0.2 Al 0.2 Fe 0.2 Mn 0.2 Cu 0.2)O 3 @PAC manifested high catalytic activity with a turnover frequency (TOF) up to 15.38 min−1 in activating PMS for degradation of antibiotic pollutant metronidazole (MNZ). Meanwhile, the high stability of HEPO gave rise to a significant decrease of cobalt leaching (0.111 mg L−1) in comparison with LaCoO 3 @PAC catalyst (1.71 mg L−1). Moreover, monolithic porous architecture of La(Co 0.2 Al 0.2 Fe 0.2 Mn 0.2 Cu 0.2)O 3 @PAC could not only endow this catalyst with easy recyclability but ensure high permeability for rapid mass transfer of guest species. Our work exemplifies the superiority of HEPO-based monolithic catalyst as a new promising activator of PMS for water remediation. [ABSTRACT FROM AUTHOR]

• The mechanism of selective catalytic reduction (SCR) on spinel TiMn 2 O 4 (001) surface has been studied via DFT simulations. • The water molecules could serve as a hydrogen exchanger and play a positive role in promoting the SCR process. • The overall SCR process is highly exothermic with modest activation barriers on TiMn 2 O 4 (001) surface. • The spinel TiMn 2 O 4 is a promising catalyst for low temperature SCR. Manganese based spinel oxides is one of the most promising catalysts for low temperature selective catalytic reduction (SCR) process due to its high activity and tunable composition. Understanding the molecular-level reaction mechanism of SCR on Mn-containing spinel oxides is of great importance for design and development of appropriate catalyst for low temperature SCR process. In this paper, density functional theory calculations were performed to address the detail SCR reaction pathways between NH 3 and NO on spinel TiMn 2 O 4 (001) surface. The full SCR process was found to be divided into four sequential stages, including the NH 3 chemisorption (stage i), NH 2 NO formation (stage ii), H migration (stage iii), and products desorption (stage iv). Notably, we found that water molecules could serve as a hydrogen exchanger and play a positive role in promoting the hydrogen migration during stage i and stage iii of the SCR process. Thermodynamically, the overall SCR process is highly exothermic with the reaction energy of -3.054 eV. Kinetically, the formation of NH 2 NO intermediate was identified as the rate determining step with a moderate activation barrier of 1.064 eV. Our results suggest that the spinel TiMn 2 O 4 is a promising catalyst for low temperature SCR. Moreover, the promoting effect of water on hydrogen diffusion should be also applicable to other chemical reactions involving hydrogen transfer. [Display omitted] [ABSTRACT FROM AUTHOR]