Fine-Tuning Synthesis and Characterization of Mono-Sized H-Beta Zeolite-Supported Palladium-Iridium Nanoparticles and Application in the Selective Hydrogenation of Acetylene

Abstract

Abstract:In this research, a mono-sized Beta zeolite support synthesized by the solvothermal method was used in the selective acetylene to ethylene hydrogenation reaction with minimum coke build up on the catalyst surface. Tetrapropylammonium hydroxide (TPAOH), tetrapropylammonium bromide (TPABr), n-butylamine, and morpholine were used as structure direct agents (SDA) in the support to obtain various shapes. The characterization results show that although the Si/(Al + SDA) ratio has no effect on the phase purity of support, it has a remarkable effect on porosity, crystal size, shape, and structure of micropores. After comparing characterization results, the developed support, based on TPAOH, was selected and modified by different metals (Ce, Ir, Ag, and Pd) using the incipient wetness co-impregnation method. Since there is an interaction between selectivity and conversion, the optimum metal content in the synthesized catalysts and reaction condition were determined to achieve the desired acetylene conversion and ethylene selectivity. The physicochemical transformation of the developed optimum catalysts was determined using different techniques. Based on the characterization and cata-test results, the catalyst which contains 0.29% Ir and 0.08% Pd presents a better performance and higher stability compared to the other catalysts due to the moderate size and mono layer dispersion of the metals on the support. The experimental results show that acetylene conversion and ethylene selectivity approach 97% and 92% at 55 • C, respectively.

Assessment of H-β zeolite as an ochratoxin binder for poultry

“…A narrow loop of type II isotherm was observed with HBZ, which confirms the formation of a well-ordered microporous structure with uniform pore size distribution (Barata-Rodrigues et al, 2003 ). The significant reduction in the amount of nitrogen adsorbed in both monolayer and the multilayer region confirms the formation of small pore size and lesser surface area (Sahooli et al, 2017 ). The capillary condensation step, which gives the direct measure of the pore diameter of the materials, has shifted towards the low relative pressure for HBZ revealing a reduction in the pore diameter of around 5 A 0 (Figure 2c ; Sahooli et al, 2017 ).…”

“…The significant reduction in the amount of nitrogen adsorbed in both monolayer and the multilayer region confirms the formation of small pore size and lesser surface area (Sahooli et al, 2017 ). The capillary condensation step, which gives the direct measure of the pore diameter of the materials, has shifted towards the low relative pressure for HBZ revealing a reduction in the pore diameter of around 5 A 0 (Figure 2c ; Sahooli et al, 2017 ). Zhang et al ( 2013 ) also reported similar physical characteristics for HBZ.…”

“…The diffractograms were recorded in the 2θ range of 0.2 to 80° with a 2θ step size of 0.01° and a step time of 10 s. The specific surface area and pore size measurement were carried out with Quantachrome Autosorb model using the Brunauer–Emmett–Teller ( BET ) method (Gonzalez et al, 2012 ). The pore size distribution was obtained from the adsorption branch of nitrogen isotherms by the Barrett–Joyner–Halenda ( BJH ) method (Sahooli et al, 2017 ). The morphology of the particles was determined by Hitachi S-4800 field emission scanning electron microscope ( HRSEM ) using an accelerating voltage of 5.0 to 20 kV (Sahooli et al, 2017 ).…”

“…The pore size distribution was obtained from the adsorption branch of nitrogen isotherms by the Barrett–Joyner–Halenda ( BJH ) method (Sahooli et al, 2017 ). The morphology of the particles was determined by Hitachi S-4800 field emission scanning electron microscope ( HRSEM ) using an accelerating voltage of 5.0 to 20 kV (Sahooli et al, 2017 ).…”

Understanding Hβ Zeolite in 1,4-Dioxane Efficiently Converts Hemicellulose-Related Sugars to Furfural

“…The XRD patterns in Figure 2a,b show that the intensities of the signal peaks at (004) and (302) corresponding to the crystal planes of Hβ-30 zeolite varied in the following order: 1,4-dioxane > THF > GVL > MIBK > DMSO > ACE > DMF > H 2 O. 40,41 All of the signal peaks of Hβ-30 zeolite after 1,4-dioxane treatment had almost the same intensities as the fresh one, whereas the (004) crystal plane was close to disappearing after treatment in DMF, ACE, and water. Furthermore, the effect of the solvent on the acidity of Hβ-30 zeolite was analyzed by Py-FTIR (Figure 2c).…”