Hydropyrolysis of Residual <i>Camellia sinensis</i> and Its Cellulose and Lignin Fractions over Nickel Nanoparticles Confined Inside Carbon Nanotube Microreactors at Atmospheric Pressure

Abstract

The potential of catalytic hydropyrolysis for the production of value-added chemicals from abundant residual biomass generated during the seasonal pruning of Camellia sinensis tea crops is evaluated. Nickel nanoparticles (∼7.2 nm) encapsulated inside the cavity of carbon nanotubes (CNTs) are prepared using an impregnation method and applied as microreactors in the catalytic hydropyrolysis of both fractionated and unfractionated biomass at atmospheric pressure. Over 86% of nanoparticles are selectively located inside the CNT channel with a Ni content of 13.4 wt % and a surface area of 129.3 m2·g–1. The influence of the catalyst/biomass ratio on the product yield and selectivity is examined, and the reaction pathways are discussed. Results reveal that the majority of oxygenated compounds are reformed into long-chain alkanes (50.5%) and aromatic hydrocarbons (33.0%) with a total oxygen content of 3.90% and a low heating value of 41.8 MJ·kg–1, comparable to commercial fuels.