Synthesis of ZSM-5 Type Ferri-aluminosilicates Using 1-C41-190H as a Template Agent and Production of Light Olefins from Methanol over These Zeolites

Abstract

Although 1-C4H9OH is an effective Template agent for the synthesis of highly crystalline ZSM-5 zeolites, ZSM-5 type ferrisilicates could not be synthesized by using 1-C4H9OH without the addition of a source of Al. Synthetic studies at various ratios of Si02/Al203and Si02/Fe203 revealed that highly crystalline ferri-aluminosilicates with a crystal size of about 3 x 8 urn were obtained when mixtures of the starting molar ratios of 0I-1-/Si02=0.19-0.25, Si02/Al203=100--400 and Si02/Fe203 =10000 (SiO2/M203= 50, -200) were heated at 180 °C for 20 h (Figs.1, 2, Tables 1, 2). Investigations of catalytic synthesis of light olefins from methanol over the prepared zeolites indicated that the selectivity for light olefins depended upon the Al content and crystallinity of the zeolites. The best crystalline ferri-aluminosilicates with a low Al content and a large crystal size, which was synthesized at the molar ratios of Si02/Al208=200 and Si02/Fe203=100, exhibited the highest selectivity of about 50-40% for ethylene and propylene at the reaction temperature of 300-320 °C (Figs.5, 7). It was noted that the addition of Fe was effective for the synthesis of zeolites with a low Al content. The Si02/Al203 ratio could be as high as 264 in the fernaluminosilicates, while it was at most 111 in the aluminosilicates prepared without Fe. However, no clear effect of Fe on the selectivity for light olefins could be observed.