Generalized high-temperature synthesis of zeolite catalysts with unpredictably high space-time yields (STYs)

Abstract

As a class of important catalysts and adsorbents, zeolites are normally prepared through hydrothermal synthesis, whereby a relatively long crystallization time and use of a large amount water solvent strongly hinder the enhancement of zeolite space-time yields (STYs), which is a critical factor for the industrial manufacturing. To overcome this limitation, herein we report a novel strategy for highly efficient zeolite synthesis by means of fast crystallization at high temperatures (200–240 °C) in the absence of water solvent. This concept significantly enhances the crystallization rates and allows drastic reduction of the time required for crystallization of the zeolite frameworks such as the crystallization of MFI from 12–24 h at 180 °C to 0.5 h at 240 °C and RUB-36 from 14 days at 140 °C to 1.5 days at 200 °C. Together with much better utilization of the reactor volume, the space-time yields (STYs) for zeolites prepared from high-temperature synthesis in the absence of water solvent can be remarkably increased. The STYs of MFI and RUB-36 are as high as 11 000 and 178 kg m⁻³ per day, which are almost two orders of magnitude higher than those of conventional hydrothermal synthesis. This novel synthesis method should be applicable for synthesizing a wide variety of zeolite structures and bears the potential for highly efficient zeolite synthesis on an industrial scale.