Particle Size Effects in the Acetylene Cyclotrimerization on Planar Model Al2O3 Thin Film Supported Pd Clusters
نویسنده
چکیده
The low-temperature cyclotrimerization of acetylene to benzene on alumina thin film supported Pd particles of controlled size has been studied by temperature-programmed desorption. The reactively formed benzene is observed to desorb in three distinctly separate features with kinetics resembling those observed for acetylene cyclotrimerization on Pd single crystals. An enhanced activity for low-temperature benzene desorption is observed for the larger Pd particles, consistent with single-crystal results that reveal that the Pd(111) surface favors low-temperature desorption of the reactively formed benzene relative to more open surfaces. Additionally, a pronounced drop-off in benzene production is observed for the smallest particles studied, suggestive of an ensemble size requirement for the reaction.
منابع مشابه
CO + O2 and CO + NO Reactions over Pd/Al2O3 Catalysts
The kinetics of the CO + NO and CO + O2 reactions have been studied over several different Pd/Al2O3 powder catalysts covering a wide range of average Pd particle sizes. The structure-insensitive nature of the CO + O2 reaction over Pd has been exploited to determine the relative dispersions in several Pd/Al2O3 powder catalysts by measuring the rate of that reaction and normalizing against surfac...
متن کاملVibrational spectroscopic studies on CO adsorption, NO adsorption CO þ NO reaction on Pd model catalysts
CO adsorption, NO adsorption and CO þ NO reaction on various Pd model catalysts have been studied using vibrational spectroscopy from ultrahigh vacuum (UHV) up to elevated pressures (B1 bar) and the kinetics of the reaction compared with the conventional high surface area Pd/g-Al2O3 catalysts. The structure sensitivity of the CO þ NO reaction on different Pd surfaces is explained using Pd(111),...
متن کاملHighly Dispersed PdNPs/α-Al2O3 Catalyst for the Selective Hydrogenation of Acetylene Prepared with Monodispersed Pd Nanoparticles
Pd nanoparticles (PdNPs) stabilized by methyl cellulose (MC) were synthesized in an aqueous solution, which are monodispersed nanoparticles. PdNPs/α-Al2O3 catalyst was prepared with monodispersed PdNPs and showed better catalytic performance than Pd/α-Al2O3 catalyst prepared by the incipient wetness impregnation method using Pd(NO3)2 as a precursor. The catalysts were characterized by transmiss...
متن کاملPartial acetylene hydrogenation over commercial Pd-Ag/α-Al2O3 catalyst promoted by ionic liquid
1-butyl-3-methyl imidazolinium hydroxide ionic liquid (BMIm[OH]) is loaded on commercial low surface area Pd-Ag/α-Al2O3 solid catalyst to enhance higher selectivity of acetylene partial hydrogenation. Different experimental techniques such as atomic absorption spectroscopy, surface area measurement and gas chromatography have been utilized to characterize chemical, structural and catalytic pro...
متن کاملAn Efficient Pd-Sn Catalyst Supported on MWNTs for Hydrogenation of High Concentrated Acetylene Feedstocks: The Potential Role of Isolated Adsorption Site
In the present study, tin-promoted Pd/MWNTs nanocatalystwas synthesized via polyol technique for application in hydrogenation of high-concentrated acetylene feedstocks. TEM images showed a restricted distribution of nanoparticles in the range of 3-5 nm. The results indicated that nanoparticles sizes were resistant to further catalyst deactivation. XRD patterns signified alloying between Pd and ...
متن کامل