Papers by Author: Rui Wang

Abstract: Carbon nano tubes (CNTs) has found applications in many fields due to its enormous versatility, however, very few report has been given on its promotive effect as support on the adsorption of NOx with solid tungstophosphoric acid (H3PW12O40), and no results on the use of surface modified CNTs in this process can be found in literatures. In this study, we have conducted systematic works on this issue and found some relations between pre-treatment method of CNTs and NOx adsorption efficiency of H3PW12O40/CNTs, and the relations between differernt impregnating solvent used in loading process and NOx adsorption efficiency of H3PW12O40/CNTs, which may be very helpful to the development of new effective adsorbent/catalyst for the adsorption-conversion of NOx. The main conclusions derived are as follows: absolute ethyl alcohol was the superior solvent to water for HPW loading on CNTs; the resultant –OH containing CNTs shows better promotive effect on the adsorption of NOx than that containing –COOH when using absolute ethyl alcohol as solvent; in both cases, with the increase of H3PW12O40 loading, the NOx adsorption efficiency tends to reach a peak value close to that in the case of pure H3PW12O40, before dropping down; compared to pre-treated activated carbon fiber, modified CNTs, especially CNTs–OH, is favorable to be used as support of H3PW12O40 for effective adsorption and even further conversion of NOx.

Abstract: Several new heteropoly compounds catalysts with pronounced activities in NO_x conversion via adsorption-decomposition process in a fixed-bed reactor were evaluated concerning the principal internal and external factors having marked effects on the process of adsorption. Results showed that substitution of H⁺ in HPW (H₃PW₁₂O₄₀•6H₂O) by NH₄⁺ results in marked enhancement of the catalyst activity, however, substitution of coordination atom W in the [PW₁₂O₄₀]^3- anion by one or more Mo atoms tends to lower the catalyst activity and such tendency deepens with the increase in the Mo atom numbers introduced. It is for the first time that the nano-effect was observed with nano (NH₄)₃PW₁₂O₄₀ catalyst, in which a 1.6% to 10.6% enhancement in NO_x adsorption efficiency was obtained in comparison with the same catalyst in normal particle size. By IR analysis, NO was found to be adsorbed via interaction with the proton of HPW structure. With the aid of GC-MS analysis, the process effectiveness for NO_x decomposition into N₂ was confirmed.