Supporting Information Non-Precious Bimetallic Catalysts for Selective Dehydrogenation of an Organic Chemical Hydride System (original) (raw)
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New Catalysts for Hydroprocessing: Bimetallic Oxynitrides
Journal of Catalysis, 1998
Bimetallic oxynitrides of the type M I M II O x N y were used as catalysts in hydrotreating reactions at 3.1 MPa and 643 K. The catalysts were prepared by nitriding bimetallic oxide precursors, where MoO 3 or WO 3 was one of the components, as described in the companion paper. The reactions were studied in a three-phase trickle-bed reactor operated at 3.1 MPa and 643 K. The feed was a model liquid mixture containing 3000 ppm sulfur (dibenzothiophene), 2000 ppm nitrogen (quinoline), 500 ppm oxygen (benzofuran), 20 wt% aromatics (tetralin), and balance aliphatics (tetradecane). The activities of the bimetallic nitrides were compared to a commercial sulfided Ni-Mo/Al 2 O 3 catalyst tested at the same conditions. The bimetallic oxynitrides were active for HDN of quinoline with V-MoO -N showing higher HDN activity than the commercial sulfided Ni-Mo-S/Al 2 O 3 catalyst. The HDS activity of the bimetallic oxynitrides ranged from 9 to 37% with Co-MoO -N showing the highest HDS activity among the oxynitrides tested. X-ray diffraction analysis of the spent catalysts indicated that the oxynitrides consisting of early transition metals (Group 4-Group 6) were tolerant of sulfur, while catalysts involving metals of Group 7 and Group 8 showed bulk sulfide phases. X-ray photoelectron spectroscopic analysis of the catalysts before and after the reaction indicated the incorporation of sulfur on the surface of the catalysts after prolonged exposure to the reactants.
Biomass Conversion and Biorefinery
Catalytic hydrotreatment is a promising technology to convert pyrolysis liquids into intermediates with improved properties. Here, we report a catalyst screening study on the catalytic hydrotreatment of pyrolysis liquids using bi- and tri-metallic nickel-based catalysts in a batch autoclave (initial hydrogen pressure of 140 bar, 350 °C, 4 h). The catalysts are characterized by a high nickel metal loading (41 to 57 wt%), promoted by Cu, Pd, Mo, and/or combination thereof, in a SiO2, SiO2-ZrO2, or SiO2-Al2O3 matrix. The hydrotreatment results were compared with a benchmark Ru/C catalyst. The results revealed that the monometallic Ni catalyst is the least active and that particularly the use of Mo as the promoter is favored when considering activity and product properties. For Mo promotion, a product oil with improved properties viz. the highest H/C molar ratio and the lowest coking tendency was obtained. A drawback when using Mo as the promoter is the relatively high methane yield, wh...
Catalyst Preparation Science and Engineering
International Standard Book Number-10: 0-8493-7088-4 (Hardcover) International Standard Book Number-13: 978-0-8493-7088-5 (Hardcover) Library of Congress Card Number 2006016073
Alternative Preparation of Improved NiMo-Alumina Deoxygenation Catalysts
Frontiers in Chemistry, 2020
This investigation deals with NiMo-alumina hydrotreating catalysts effective in the deoxygenation of rapeseed oil. The main goal was to compare catalyst structure and their deoxygenation performance and to link these parameters to reveal important structural information regarding the catalyst's intended use. Catalysts were prepared from different precursors (nickel acetate tetrahydrate/molybdenyl acetylacetonate in ethanol and water vs. nickel nitrate hexahydrate/ammonium heptamolybdate tetrahydrate in water), which resulted in their contrasting structural arrangement. These changes were characterized by elemental composition determination, UV-Vis diffuse reflectance spectroscopy, temperature programmed reduction by hydrogen, nitrogen physisorption at 77 K, scanning and transmission electron microscopies, and deoxygenation of rapeseed oil. The critical aspect of high oxygen elimination was a homogeneous dispersion of NiO and MoO3 phases on the support. It subsequently led to the effective transformation of the oxide form of a catalyst to its active sulfide form well-dispersed on the support. On the other hand, the formation of bulk MoO3 resulted in the separate bulk phase and lower extent of sulfidation.
Catalysts featuring 2, 5, and 10 wt % silver supported on alumina were prepared by the deposition precipitation method and activated under hydrogen. All catalysts were characterized by Brunauer−Emmett−Teller (BET) measurements, inductively coupled plasma-optical emission spectrometry (ICP-OES), backscattered electron scanning electron microscopy (BSE-SEM), highresolution transmission electron microscopy (HR-TEM), hydrogen-temperatureprogrammed reduction (H 2-TPR), H 2-chemisorption, thermogravimetric analysis (TGA), infrared (IR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, and isopropylamine (IPA) TPD and evaluated in a continuous plug flow fixed-bed reactor. Metal nanoparticles with average sizes of 4.5, 11.5, and 21.1 nm were identified by HR-TEM for the 2, 5, and 10 wt % Ag/Al 2 O 3 catalysts, respectively. A conversion of 99% was observed for 1-octyne over particles between 10 and 15 nm in size, with stable operation up to 24 h (decreasing thereafter) at a temperature of 140°C and a pressure of 30 bar in the competitive hydrogenation reaction. No conversion of 1octene was noted in competitive reactions (mixed 1-octyne and 1-octene feed) but rather a gain of 1-octene throughout the 72 h time-on-stream. The performance of all catalysts was influenced by both the metal and support, where the latter impacted the overall acidity of the catalysts, thus affecting their long-term stability.
Hydrotalcites as Precursors of Catalytic Materials in Comparison with the Metal-Supported Catalysts
This work compares catalytic properties of materials prepared by thermal pre-treatment of hydrotalcite-like precursors and metal-supported materials. The attention is focused on two types of materials and two different reactions. Firstly, the activity of Ni-AI mixed oxides prepared by thermal pre-treatment of Ni-Al hydrotalcites is compared with that of supported Ni-based catalysts (Ni-alumina, Ni-alumina/meso) in the oxidative dehydrogenation of ethane and propane. The critical role in the activity and selectivity has been assigned to the population of NiO and its interaction with the support. Secondly, the attention is focused on basic catalysts and their activity in transesterification of rapeseed oil. The activity/stability of Mg-Al mixed oxides prepared by thermal pre-treatment of Mg-Al hydrotalcites is compared with that of supported potassium catalysts representing one of the most discussed solid catalysts for transesterification.