Selective hydrogenation of reformate oils over amorphous NiB/SiO2 catalyst

Discovery of Alloy Catalysts Beyond Pd for Selective Hydrogenation of Reformate via First-Principle Screening with Consideration of H-Coverage

The highly selective hydrogenation to remove olefins is a significant refining approach for the reformate. Herein, a library of transition metal for reformate hydrogenation is tested experimentally to validate the predictive level of catalytic activity from our theoretical framework, which combines ab initio calculations and microkinetic modeling, with consideration of surface H-coverage effect on hydrogenation kinetics. The favorable H coverage of specific alloy surface under relevant hydrogenation condition, is found to be determined by its corresponding alloy composition. Besides, olefin hydrogenation rate is determined as a function of two descriptors, i.e. H coverage and binding energies of atomic hydrogen, paving the way to computationally screen on metal component in the periodic table. Evaluation of 172 bimetallic alloys based on the activity volcano map, as well as benzene hydrogenation rate, identifies prospective superior candidates and experimentally confirms that Zn3Ir1 outperforms pure Pd catalysts for the selective hydrogenation refining of reformate. The insights into H-coverage-related microkinetic modelling have enabled us to both theoretically understand experimental findings and identify novel catalysts, thus, bridging the gap between first-principle simulations and industrial applications. This work provides useful guidance for experimental catalyst design, which can be easily extended to other hydrogenation reaction.

Immobilization of Amorphous NiB Nanoparticles on Mesoporous Supports: Superior Catalysis for Controllably Hydrolyzing NaBH4 to Release H2

Taking Ni(CH3COO)2 and NaBH4 as the Ni and B sources and selecting three kinds of mesoporous materials (carbon nanotube (CNTs), activated carbon (AC), and silica (SiO2)) as supports, the liquid-phase reduction-in situ deposition tactics was employed to fabricate the amorphous alloy NiB and its corresponding supported catalysts (NiB/CNTs, NiB/AC, and NiB/SiO2) with assistance of a suitable stabilizer and ultrasonic treatment. The X-ray powder diffraction, transmission electron microscopy, and inductively coupled plasma atomic emission spectrometry were used to characterize the morphology and phase composition of the products. The catalytic activity of the four products for the hydrolytic hydrogen release in NaBH4 solution under different conditions was minutely investigated. The research results indicate that the as-fabricated products belong to amorphous alloy nanoparticles with the single phase and higher purity. The satisfactory dispersion and stronger interaction between NiB and CNTs give NiB/CNTs the best thermal stability. All the four catalysts hold satisfactory catalysis, but their catalytic abilities are obviously discrepant, in the following order: NiB/CNTs > NiB/SiO2 > NiB > NiB/AC. The mean reaction turnover frequency of the NiB/CNTs catalyst at both 318 K and 298 K separately comes up to 28206 ml(H2)·min−1·g−1(NiB) and 13424 ml(H2)·min−1·g−1(NiB), with an apparent activation energy of 47.37 kJ·mol−1. The proposed synthetic strategy could be extended to the fabrication of other similar amorphous alloy catalysts, expected for extensive application prospect.

New Insights into the Electrocatalytic Mechanism of Methanol Oxidation on Amorphous Ni-B-Co Nanoparticles in Alkaline Media

Despite an increased interest in sustainable energy conversion systems, there have been limited studies investigating the electrocatalytic reaction mechanism of methanol oxidation on Ni-based amorphous materials in alkaline media. A thorough understanding of such mechanisms would aid in the development of amorphous catalytic materials for methanol oxidation reactions. In the present work, amorphous Ni-B and Ni-B-Co nanoparticles were prepared by a simple chemical reduction, and their electrocatalytic properties were investigated by cyclic voltammetry measurements. The diffusion coefficients (D0) for Ni-B, Ni-B-Co0.02, Ni-B-Co0.05, and Ni-B-Co0.1 nanoparticles were calculated to be 1.28 × 10−9, 2.35 × 10−9, 4.48 × 10−9 and 2.67 × 10−9 cm2 s−1, respectively. The reaction order of methanol in the studied transformation was approximately 0.5 for all studied catalysts, whereas the reaction order of the hydroxide ion was nearly 1. The activation energy (Ea) values of the reaction were also calculated for the Ni-B and Ni-B-Co nanoparticle systems. Based on our kinetic studies, a mechanism for the methanol oxidation reaction was proposed which involved formation of an electrocatalytic layer on the surface of amorphous Ni–B and Ni-B-Co nanoparticles. And methanol and hydroxide ions could diffuse freely through this three-dimensional porous conductive layer.