chemical-precipitation-method-for-synthesis-nb2o5-modified-bulk

Chemical Precipitation Method for the Synthesis of Nb<sub>2</sub>O<sub>5</sub> Modified Bulk Nickel Catalysts with High Specific Surface Area

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of ...

tuning-acidity-pt-cnts-catalysts-for-hydrodeoxygenation-diphenyl

Tuning the Acidity of Pt/ CNTs Catalysts for Hydrodeoxygenation of Diphenyl Ether

We herein present a method for the synthesis of HNbWO6, HNbMoO6, HTaWO6 solid acid nanosheet modified Pt/CNTs. By varying the weight of various solid acid ...

Dalian University of Technology

Effective utilization of coal bed methane is very significant for energy utilization and environment protection. Catalytic combustion of methane is a promising way to eliminate trace amounts of oxygen in the coal bed methane and the key to this technology is the development of high-efficiency catalysts. Herein, we report a series of CeLaO(x = 0-0.8) monolithic catalysts for the catalytic combustion of methane, which are prepared by citric acid method. The structural characterization shows that the substitution of La enhance the oxygen vacancy concentration and reducibility of the supports and promote the migration of the surface oxygen, as a result improve the catalytic activity of CeO. M-CeLaO(monolithic catalyst, CeLaOcoated on cordierite honeycomb) exhibits outstanding activity for methane combustion, and the temperature for 10 and 90% methane conversion are 495 and 580 °C, respectively. Additionally, CeLaOmonolithic catalyst presents excellent stability at high temperature. These CeLaOmonolithic materials with a small amount of La incorporation therefore show promises as highly efficient solid solution catalysts for lean-oxygen methane combustion. Graphical abstract ᅟ.

Enhanced activity and stability of La-doped CeOmonolithic catalysts for lean-oxygen methane combustion.

Bimetallic Co-Re/TiO catalysts were developed for efficient citral hydrogenation. Bimetallic catalysts were prepared by co-impregnation (CI), successive-impregnation (SI), and surface redox method (SR). The arrangement between the Co and Re species on these systems was fully characterized using several techniques (TEM-energy-dispersive X-ray spectroscopy, H temperature-programmed reduction, temperature-programmed desorption, XRD, CO FTIR spectroscopy, model reaction of cyclohexane dehydrogenation), and their catalytic performances were evaluated for the selective hydrogenation of citral towards unsaturated alcohols. The Re and Co species are completely isolated in the CI sample, presenting a very limited Co-Re interaction. In SI samples, the metals coexist in a Janus-type structure with a concentration of Re around Co. Decoration/core-shell structures are observed for SR samples resulting from the redox exchange between the metallic surface of the parent Co/TiO catalyst and the Re species of the modifier precursor salt. The contact degree between the two metals gradually increases as follows: Isolated structure (CI)<Janus-type structure(SI)<decoration/core-shell structure (SR). The unchanging structure of all SI samples independent of the Re loading leads to similar electron transfer, and the increase in Re content results in agglomeration of Re, thus decreasing the catalytic activity. Density-of-state (DOS) calculations prove that the high valence of Re is a disadvantage for the hydrogenation reaction. For SR samples, the increase of Re loading contributes to the electron transfer from Re to Co that is consistent with a change of structure from decoration to core-shell. The lack of directly accessible Co atoms for SR catalysts with fully coated structure decreases the efficiency of Re reduction. The presence of Co-Re interaction resulting from the close contact between metals plays a dominant role in the hydrogenation of citral. Nevertheless, an excessively high contact degree is unnecessary for citral hydrogenation once Co-Re interaction has formed.

Supported Co-Re Bimetallic Catalysts with Different Structures as Efficient Catalysts for Hydrogenation of Citral.

The fabrication of bimetallic catalysts has been taken great focus in the concept of heterogeneous catalysis due to their high efficiency and economic concerns. In this work, a series of bimetallic Ru-Re catalysts were designed and synthesized for the selective hydrogenation of dimethyl terephthalate (DMT) to 1,4-cyclohexane dicarboxylate (DMCD) under mild condition. Characterization techniques including the XRD, TEM, STEM-HAADF EDX elemental mapping, H2-TPR, and XPS were used to study the surface chemical property, the morphology, as well as the catalytic behavior of different samples. It was revealed that the monometallic Ru catalyst already has the capacity to activate and transform DMT into DMCD. Whilst the promotion effect can be optimized to a maximum with only small amount of Re, with the mass ratio of Ru/Re as 10:1. It was also revealed that the addition of Re could largely enhance the distribution of surface active metal species, facilitate the charge transfer between Ru and Re, as well as strengthen the Ru-Re synergistic interaction, which further led to the modification of the redox ability and the catalytic performances of samples. However, excessive addition of Re caused strong interaction between Ru and Re, and further limited the H₂ activation and the seasonable release of the active reducible metal species, which was responsible for the depressed catalytic performances in the presence of higher Re loading. The RuRe/AC catalyst displayed the DMT conversion of 82% with DMCD selectivity of 96% under mild condition of 70 °C at 3 MPa. The specific rate of RuRe/AC based on per gram of Ru was 0.44 mol·g Ru·h.

Article Total : 2	Year
Publication title	2018
Publication title	2019

Article	Year
Enhanced activity and stability of La-doped CeOmonolithic catalysts for lean-oxygen methane combustion. Environmental science and pollution research international\| PubMed ID: 29222662	2017
Supported Co-Re Bimetallic Catalysts with Different Structures as Efficient Catalysts for Hydrogenation of Citral. ChemSusChem\| PubMed ID: 30620120	2019
Selective Hydrogenation of Dimethyl Terephthalate to 1,4-Cyclohexane Dicarboxylate by Highly Dispersed Bimetallic Ru-Re/AC Catalysts. Journal of nanoscience and nanotechnology\| PubMed ID: 31383114	2020

Chuang Li

Biography

JoVE Journal Publications

Other Publications