Preparation, Characterization and Catalytic Performance of ZnO-SBA-15 Catalysts

Abstract

The series of ZnO-SBA-15 catalysts with 0.9wt% to 8.5wt% ZnO content have been synthesized by solvothermal impregnated of Zn acetate in ethanol on mesoporous silica SBA-15 platelets in order to maximize the methyl ester selectivity in transesterification reaction. The properties of these catalyst were characterized by N2 adsorption-desorption isotherm, NH3 temperature-programmed desorption, SEM, and XRD. The results showed that the ordered mesoporous structure of SBA-15 was remained with specific surface areas above 500 m2/g and a narrow pore size distribution observed with the mean pore size around 60 Å after ZnO modification. The strength of the acid sites and total acid amount of ZnO-SBA-15 catalysts is varied with number of ZnO loadings. The synthesized ZnO-SBA-15 catalyst was tested for catalytic activity in transesterification of crude Jatropha oil. It was found that at 200 °C for 2 h reaction of the ZnO-SBA-15 catalysts with acid capacities of 0.36-1.29 mmol H+/g-catal gave 68-98wt% of FAME yields and 0.4-1.4wt% of FFA yields which are comparable to the pure ZnO.

On the Role of Sn Segregation of Pt-Sn Catalysts for Propane Dehydrogenation

“…Possible effects of acid sites introduced during the acid etching process on performance were excluded because NH 3 -TPD experiments do not show any acid sites produced during acid etching (Figure S4). − After the acid etching-reduction process, the initial propane conversion over RE-Pt-Sn/SBA-15 is 37% and decreases to 23% after reaction for 480 min (Figure a). The propene selectivity is 92% (Figure a), and the carbon balance is 0.98 (Figure b), consistent with Pt-Sn/SBA-15.…”

Comparison of the synthesis routes for the ZnO/porous silica nanocomposite

“…In the present study, we focused on the semiconductor zinc oxide NPs. Nanocrystalline ZnO is one of the potential candidates for applications in optoelectronic devices [16], chemical gas sensors [17], solar cells [18], optical switches [19], as a catalyst [15], etc. Moreover, ZnO has been paid considerable attention as a promising electronic luminescent device material that enables producing light-emitting devices in the ultra-violet region.…”

“…While incorporation of NPs into molecular sieves can solve the stability and agglomeration problems, the insertion process is a challenge by itself. Various fabrication techniques to produce NPs inside the molecular sieves have been proposed, namely: wet impregnation, sol-gel method, radio-frequency sputtering, one-pot surfactant-assisted procedure, direct incorporation, grafting with organometallic compounds and others [7][8][9][10][11][12][13][14][15].…”