Development of Ni Nanoparticle Encapsulated with Silicalite-1 Catalyst for High Activity Steam Reforming of Bioethanol with High Sintering Resistance and Coke Suppression

Abstract

Steam reforming of bioethanol is a potential reaction for H2 production. The development of active Ni catalysts with sintering resistance, coking resistance and thermal stability is indispensable for practical application. In this study, the encapsulation structure of Ni nanoparticles inside Silicalite-1 was proposed as a catalyst (Ni@Silicalite-1). The catalyst was prepared by hydrothermal synthesis using Ni-phyllosilicate as a Ni precursor. An investigation of catalytic activity was conducted at 500–800 °C, along with an investigation of catalyst properties, including surface morphology, Ni properties, and coke formation on the spent catalysts, compared to a conventional Ni/Silicalite-1. Ni@Silicalite-1 exhibits a higher ethanol conversion, hydrogen production, and selectivity towards C1 products. Especially in a kinetic control condition (500–600 °C), Ni@Silicalite-1 exhibits 46.8% in ethanol conversion at 500 °C and two times higher in C2-to-C1 conversion at 600 °C than that of Ni/Silicalite-1. Moreover, a significant coke suppression of 2–5 times reduction form that of impregnation catalyst is obtained for Ni@Silicalite-1 in various reaction temperatures. It also shows a sintering resistance as maintaining the Ni size at 4.0–4.1 nm after ESR at high temperature (800 °C 4 h). Therefore, the encapsulation structure of ultrafine Ni nanoparticles inside Silicalite-1 is promising for bioethanol steam reforming.