para-Selectivity of silicalite-1 coated MFI type galloaluminosilicate in aromatization of light alkanes

Abstract

MFI type galloaluminosilicates (GaAlMFI) were coated with inert silicalite-1 layers. The silicalite-1 coating could improve the para-selectivity for xylene production in aromatization of propane. In the silicalite-1 coating step, low alkali concentration in the synthesis solution enhanced para-selectivity. A proton-exchange procedure also had an impact on the para-selectivity. Significant decrease of para-selectivity was observed over the silicalite-1 coated GaAlMFI with repeated proton-exchange. From the 71 Ga and 27 Al MAS NMR measurements, demetalation occurred during the proton-exchange process, and those metal species is likely to become catalytically active sites without para-selectivity. From the aromatization of propane and n-butane, para-selectivity in n-butane aromatization was found to be higher than that in propane aromatization. From the product distribution, naphthalene and its derivatives were easier to be produced in propane aromatization compared to n-butane aromatization. The formation of naphthalene and its derivatives may relate to decrease in the para-selectivity in propane aromatization.

Light Paraffinic Naphtha to BTX Aromatics over Metal‐Modified Pt/ZSM‐5

“…[4][5][6][7][8][9] Impregnation of metals into the ZSM-5 structure enhances aromatization selectivity in such a way that the acidity of ZSM-5 provides the cracking, while metal function is responsible for dehydrogenation, which converts olefins into aromatics. [10,11] Moreover, the metal component reduces severe cracking selectivity toward lower paraffin's and produces hydrogen as by-product. The effect of modified gallium and zinc HZSM-5 catalysts for n-hexane and light naphtha on aromatization has been studied by several research groups.…”

Direct and selective conversion of methanol to para-xylene over Zn ion doped ZSM-5/silicalite-1 core-shell zeolite catalyst

“…In our previous work, silicalite-1 (Al-free MFI type zeolite) coated catalysts showed much higher catalytic performance on various reaction systems [38][39][40][41][42][43][44][45][46] .…”

Fabrication of Co/P25 coated with thin nitrogen-doped carbon shells (Co/P25/NC) as an efficient electrocatalyst for oxygen reduction reaction (ORR)

“…Previously, we synthesized various core-shell structured materials. [54][55][56][57][58][59][60][61][62][63][64][65] In particular, we demonstrated that thin carbon shells (graphene) were deposited on P25 (commercially available and inexpensive TiO 2 ) by chemical vapour deposition (CVD) using methanol or propylene as carbon source. [65] In addition, we prepared Co nanoparticles modified carbon nanotubes with good ORR catalytic performance using poly vinyl pyrrolidone (PVP) as a protecting agent and NaBH 4 as a reduction agent.…”