Catalytic Activity For Decomposition Research Articles

Study of reverse water gas shift reaction by TPD, TPR and CO 2 hydrogenation over potassium-promoted Cu/SiO 2 catalyst

The reverse water gas shift (RWGS) reaction over Cu/SiO 2 with and without potassium promoter was studied by means of CO 2 hydrogenation, temperature programmed reduction (TPR) and temperature programmed desorption (TPD). After addition of even a little amount of potassium, Cu/K 2O/SiO 2 obviously offers better catalytic activity than Cu/SiO 2. The coverage of formate species increases on Cu/K catalyst. TPD of CO 2 adsorbed on Cu/K 2O/SiO 2 and TPR profile of Cu/K 2O/SiO 2 showed that new active sites could be created at interface between Cu and K. The main role of K 2O was to provide catalytic activity for decomposition of formates, besides acting as a promoter for CO 2 adsorption. A new reaction mechanism was suggested. Hydrogen was dissociatively adsorbed on Cu and could spill over to K 2O to associate with CO 2. This resulted in the formation of formate species for the production of CO.

Reactivity of glycidyl‐methacrylate‐grafted cellulose prepared by means of photografting

AbstractPhotografting was applied to functionalize cellulose, that is, epoxy groups were introduced into the cellulose substrate by photografting of glycidyl methacrylate (GMA) using hydrogen peroxide as a photoinitiator. Dissolving pulp from softwoods was used as the cellulose sample. The GMA‐grafted cellulose (G‐Cell) was subjected to the following examinations in comparision with epoxy‐activated cellulose (E‐Cell) prepared by reaction with epichlorohydrin: (1) reactivity of G‐Cell towards amines such as ethylenediamine, tetramethylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine; (2) ability of the aminated celluloses obtained by examination (1) to adsorb cupric ion; and (3) catalytic activity of the aminated cellulose–cupric ion complexes prepared by examination (2) for decomposition of hydrogen peroxide. The amount of amine residue introduced into the substrate was higher for E‐Cell than G‐Cell, showing the existence of epoxy groups in G‐Cell which cannot contribute to the reaction. The ability of the aminated celluloses to adsorb cupric ion was nearly equal for G‐Cell and E‐Cell though tetramethylenediamine and hexamethylenediamine‐introduced samples did not show the ability. It was found that all complexes prepared by reaction of the aminated cellulose with cupric ion exhibited catalytic activity for decomposition of hydrogen peroxide. © 1995 John Wiley & Sons, Inc.

Preparation of polymer-supported schiff base iron (III) complexes and their catalytic activity for decomposition of hydrogen peroxide

Polymeric substrates containing salicylidenimine ligands as discrete units can be obtained by reacting chloromethylated divinylbenzene styrene copolymer with amines, followed by condensation with salicylaldehyde. Polymer-supported Schiff base iron (III) complexes have been prepared and their IR spectra and Mossbauer spectra measured. Catalytic activity of supported complexes have been tested using decomposition of hydrogen peroxide as a model reaction.

Base properties of zeolite catalysts

Distributions of base strengths were determined using indicator techniques and i.r. spectroscopic studies of acetic acid adsorbed on samples of faujasite-type zeolites. The results show that base sites of variou zeolites differ significantly in both their strength and nature. Among sodium forms of the zeolites, NaX appeared to exhibit higher strength and concentrations of base sites than NaY. For hydrogen-sodium forms, the situation was reversed: HNaY prevailed over HNaX. The total basicities of the hydrogen—sodium zeolites were considerably higher than those of the sodium forms, due to contributions from both hydroxyl groups and oxygen ions of (AlO 4) − tetrahedra; whereas the latter exhibited Lewis basicity alone. Nonetheless, the higher basicities of the HNaY and HNaX zeolites do not correlate with their catalytic activity for decomposition of diacetone alcohol to acetone, a model base-catalysed reaction. The relatively poor conversions to acetone are examined within the context of base strengths and the high acidity of HNaX and HNaY since another reaction pathway, acid-catalysed formation of mesityl oxide, was also observed.