Keyi Tao

Catalytic dechlorination of monochlorobenzene with a new type of nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant

A unique type of nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant was prepared and used for dechlorination of monochlorobenzene (MCB). The sample Ni(B)/Fe(B) was synthesized by an electroless plating method, in which nanoscale Ni(B) was deposited on the surface of nanoscale Fe(B) synthesized by chemical reduction. The results suggest that the nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant has higher dechlorination efficiency than Ni/Fe(B) catalytic reductant prepared by replacing Fe(B) with Ni(2+) in aqueous solution. The Ni content was found to be an important factor in catalytic dechlorination, with the dechlorination rate increasing with Ni content. The electroless plating method improve the efficiency of the Ni(2+) in the solution. Dechlorination takes place with the existence of nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant via a pseudo-first-order reaction.

Synthesis of nickel nanoparticles supported on metal oxides using electroless plating: Controlling the dispersion and size of nickel nanoparticles

Nickel nanoparticles supported on metal oxides were prepared by a modified electroless nickel-plating method. The process and mechanism of electroless plating were studied by changing the active metal (Ag) loading, acidity, and surface area of metal oxides and were characterized by UV-vis spectroscopy, transmission electron microscopy, scanning electron microscopy, and H(2) chemisorption. The results showed that the dispersion of nickel nanoparticles was dependent on the interface reaction between the metal oxide and the plating solution or the active metal and the plating solution. The Ag loading and acidity of the metal oxide mainly affected the interface reaction to change the dispersion of nickel nanoparticles. The use of ultrasonic waves and microwaves and the change of solvents from water to ethylene glycol in the electroless plating could affect the dispersion and size of nickel nanoparticles.

Synthesis and characterization of a porous amorphous Ni–B catalyst on titania by silver-catalyzed electroless plating

An amorphous Ni–B/TiO2 catalyst has been synthesized by silver-catalyzed electroless nickel plating. The amorphous structure of Ni–B nanoparticles was characterized by X-ray diffraction (XRD) and selected area electron diffraction (SAED). A transmission electron micrograph (TEM) of the Ni–B/TiO2 showed particles with size ranging from 30 to 50 nm were homogeneously dispersed over TiO2 support. High-resolution transmission electron microscopy (HRTEM) indicated that the Ni–B nanoparticles presented a porous and flower-like morphology, which was different from the solid sphere of conventional Ni–B particles prepared by impregnation–reduction method. To investigate the formation process of the porous Ni–B particles, the diffusion of nickel nuclei and the growth of Ni–B particles were characterized. The as-prepared porous Ni–B/TiO2 catalyst exhibited superior catalytic activities in the hydrogenation reactions to those of catalysts prepared by conventional methods.

Preparation and catalytic properties of amorphous alloys in hydrogenation of sulfolene

A series of NiB(P) and NiCoB amorphous alloys were prepared by chemical reduction. Their catalytic activities in hydrogenation of sulfolene were evaluated in a 250 ml stainless autoclave. Influences of solvent and preparation temperature on the catalytic activity of NiB amorphous alloy were studied. Effects of reaction temperature and stirring rate on the catalytic properties of NiB amorphous alloy were researched; Raney Ni properties were also studied. The relationship between particle size of NiB, NiP and NiPB amorphous alloys and their catalytic behaviors has been discussed according to SEM, TEM and ICP results. Comparing the activities of NiCoB amorphous alloys with NiB, CoB and Raney Ni catalysts, we found that, NiCoB amorphous alloys with mole ratio of Ni/Co at 2.4 have much higher activity in hydrogenation of sulfolene.

Low-temperature approach to synthesize iron nitride from amorphous iron.

Iron nitride was prepared by a nitridation reaction in NH 3 using amorphous iron as precursor. The precursor was prepared at ambient temperature through the process of reducing ferrous sulfate by potassium borohydride, followed by the nitridation at different temperatures. The nitridation reaction occurred at 548 K, and -Fe 2-3N was formed at 573 K. The reaction temperature was much lower than that using crystallized iron because of the characteristics of the amorphous materials. The existence of a small quantity of boron (1.6 wt.%) improved the stability of the amorphous precursor, which guaranteed an amorphous iron precursor at nitriding temperatures in excess of 548 K.

Effect of modified industrial zeolite beta on one-step catalytic hydration of propene to isopropanol

Abstract In order to improve the yield of isopropanol, we used a new type of zeolite beta catalysts. By using acid-exchange and steaming treatments, various types and contents of binder, different forming and exchanging conditions, we have studied the technological conditions for preparing zeolite beta. As a result, we obtained a new kind of catalyst. Using XRD, SEM, IR, TPD, AAS, etc., we studied the effects of structure and acidity changes of modified zeolite beta on the reaction. The catalytic performance under industrial production conditions was studied. The IPA yield was from 9% to 10%, better than the value of 4% of the original industrial catalyst. Under these circumstances, we scaled the experiment up at the Jinzhou Petrochemical Company and achieved good results, opening up new industrial perspectives.

A novel route to the synthesis of bulk and well dispersed alumina-supported Ni2Mo3N catalystsvia single-step hydrogen thermal treatment

In this study, a facile method for the synthesis of bulk and alumina-supported Ni2Mo3N is described. The synthesis is based on the heat treatment of a mixed-salt precursor in a H2 flow at 873 K. The mixed-salt precursor is obtained by evaporating ammonia solution of Ni(CH3COO)2 and (NH4)6Mo7O24 with a fixed Ni/Mo molar ratio of 2 : 3. The formation process of the bimetallic molybdenum nitride has been investigated, which indicates that the labile NH4+ contained in the inorganic salt precursor is utilized as N source to form Ni2Mo3N in the H2 flow when elemental nickel is present. The high NH3 flow rate required in the conventional temperature-programmed nitridation method is not necessary in this hydrogen thermal treatment method. Alumina-supported Ni2Mo3N has also been successfully prepared by this method. The resultant catalyst has better dispersion of Ni2Mo3N and exhibits higher catalytic activity compared to the catalyst prepared by the conventional method.

Promotion effects of alkali metal halides on the oxidative methylation of toluene with methane over KY zeolite catalysts

Effects of alkali metal halides promoter on the oxidative methylation of toluene with methane over KY zeolite catalysts were systematically studied. In terms of the catalytic activity for the oxidative methylation of toluene with methane over those catalysts, the following order was observed: NaBr/KY>KBr/KY>NaCl/KY. The C8 products containing much styrene were gained over alkali metal bromide promoted KY zeolite catalysts. The acidity and basicity of these catalysts were studied by using NH3-TPD and formic acid-TPD. # 1999 Elsevier Science B.V. All rights reserved.

Preparation and Catalytic Performance of Ni-B Amorphous Alloy Supported by Chitosan/SiO2

Ni-B amorphous catalyst supported by chitosan (CS)-modified silica (Ni-B/CS/SiO2) was prepared using impregnation-reduction method. The as-prepared catalysts were characterized using X-ray powder diffraction (XRD), fourier transform infrared (FTIR) spetra, inductively coupled plasma (ICP) spectrometer, Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). The results showed that the particle sizes, the surface content of Ni active species, and catalytic activity were improved by introducing chitosan to the surface of silica. In the hydrogenation of furfuryl alcohol (FA) to tetrahydrofurfuryl alcohol (THFA), the amorphous Ni-B/CS/SiO2 catalyst exhibited superior catalytic activity to the corresponding traditional Ni-B/SiO2 amorphous catalyst and Raney Ni.

A simple synthesis route and characterisation of Co3Mo3C

A simple, one-step thermal decomposition method for the preparation of Co(3)Mo(3)C is reported in this paper. In this novel synthesis route, a mixed-salt precursor, containing Co(CH(3)COO)(2) x 4H(2)O, (HMT)(2)(NH(4))(4)Mo(7)O(24) x 2H(2)O (HMT = hexamethylenetetramine), and excess HMT is directly decomposed to the bimetallic carbide under flowing argon at 1023 K. The role of HMT in the preparation process has been investigated and a detailed reaction mechanism is proposed based on the experimental results. The bimetallic carbide is characterised by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, BET surface area measurement and X-ray photoelectron spectroscopy. Furthermore, the activity of the as-prepared Co(3)Mo(3)C is evaluated by a 3-methylpyridine hydrodenitrogenation (HDN) reaction. The catalyst produced from this method provides better reactivity compared to the Co(3)Mo(3)C catalyst prepared by the conventional temperature-programmed reduction method.