One-Step Hydropyrolysis and Hydrotreating Tandem Reactions of Miscanthus × giganteus Using Ni Impregnated ZSM-5/MCM-41 Composites

In this study, we propose that the multistep, tandem catalytic fast hydropyrolysis (CFHP) and hydrotreatment reactions of biomass to produce gasoline and diesel grade biofuels can be conducted in a single step process using a composite of Ni-ZSM-5 microcrystals encapsulated in spherical particles of Ni-MCM-41 (Ni-ZSM-5/Ni-MCM-41). The composite has been successfully prepared via a one-step aerosol method and characterized by N 2 adsorption–desorption, X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope (TEM), pyridine adsorption, inductively coupled plasma-optical emission spectrometry (ICP-OES), and H 2 chemisorption. The composite has been tested for one-stage CFHP and hydrotreatment of Miscanthus × giganteus at 600 and 500 °C. The product yields and distribution derived from the one-stage CFHP and hydrotreatment of Miscanthus × giganteus using the Ni-ZSM-5/Ni-MCM-41 composite were compared to those of a typical two-stage process, with Ni-ZSM-5 in the first stage (CFHP) and Ni-MCM-41 in the second stage (hydrotreatment). Additional experiments were carried out using Ni-ZSM-5, Ni-ZSM-5/MCM-41, and ZSM-5/Ni-MCM-41 composites, as well as physical mixtures of Ni-ZSM-5 and Ni-MCM-41 to obtain further insights into the role of each part of the composites to the product yields and distribution derived from the one-stage CFHP and hydrotreatment reaction. The comparison of results showed that the Ni-ZSM-5/Ni-MCM-41 composite enhanced the production of alkanes and methane without sacrificing the yield to monoaromatic hydrocarbons. Therefore, this study proves that such a unique composite can complete the two-step tandem reactions in one single step, leading to a self-sustainable and intensified process.