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Investigating the Cold Plasma Surface Modification of Kaolin- and Attapulgite-Bound Zeolite A
Mahboobeh Ejtemaei,Sepehr Sadighi,Mehdi Rashidzadeh,Sirous Khorram,Jan O. Back,Simon Penner,Michael F. Noisternig,Dariush Salari,Aligholi Niaei 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.106 No.-
Hydrophilic zeolites with low catalytic activity are considered as suitable adsorbents for drying gasstreams containing olefinic compounds. In this contribution, the surface treatment of kaolin and attapulgite/zeolite A extrudates is investigated using argon glow discharge plasma. The zeolite is synthesizedfrom kaolin using the hydrothermal method. Surface and bulk characterization is performed using X-raydiffraction (XRD), scanning electron microscopy (SEM), N2 physisorption, Fourier-transform infrared (FTIR)spectroscopy, temperature-programmed-desorption (TPD) of NH3 and X-ray photoelectron spectroscopy(XPS) techniques. Plasma treatment increases surface area and pore volume, but it decreasesthe weak acidic site density of the extrudates. The obtained results show that attapulgite/zeolite extrudatesare more affected by plasma treatment than kaolin/zeolite extrudates. The catalytic activity ofuntreated and plasma-treated extrudates are compared with respect to coke formation resulting from1-butene and 1,3-butadiene. The plasma-treated sample is more resistant to coke formation (35%decrease compared to untreated one). The potassium contents of extrudates decreased as a result of sputteringloosely bound potassium cations on the crystal surface by argon ions, which led to a decrease inwater sorption capacity (by 15% of the initial sorption capacity).
Neda Kalantari,Maged F. Bekheet,Parastoo Delir Kheyrollahi Nezhad,Jan O. Back,Ali Farzi,Simon Penner,Nagihan Delibas,Sabine Schwarz,Johannes Bernardi,Dariush Salari,Aligholi Niaei 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.111 No.-
We introduced chromium and boron into the hierarchical structure of ZSM-5 by following an incipientwet impregnation and hydrothermal synthesis approach to enhance the performance of the catalystsin the methanol-to-propylene process. Crystal structure, preferred orientation, and crystal symmetry ofsynthesized zeolites were discussed using Rietveld refinement and revealed that all synthesized zeolitescrystallized in a monoclinic structure, whereas the boron-incorporated sample exhibited an orthorhombicsymmetry. Large-scale defect-free single-crystalline structures of hierarchical zeolite created by CTABand F127 mesoporogens are confirmed by electron microscopy and magic angle spinning nuclear magneticresonance (MAS NMR). The formation of surface metal oxides and extra-framework metal oxidescaused changes in the electronic structure of the components as visible in Si 2p and O 1s spectra. The predominantpresence of OH groups and the higher Cr (VI) /Cr (III) ratio account for the better performanceof impregnated chromium-ZSM-5 especially in the production of light olefins. The introduction of boronby impregnation further preserved the preferred growth orientation, hierarchical structure with highcrystallinity and caused surface acidity changes in favor of increasing propylene selectivity to 67% witha propylene/ethylene ratio of close to 8.