Lignocellulosic biomass pyrolysis: A review on the pretreatment and catalysts

Facing the dual challenges of fossil energy depletion and environmental pollution, the development of clean energy, particularly carbon-neutral biomass, has gained significant attention. Biomass thermochemical conversion offers an efficient pathway to produce high-value chemicals. This review systematically examines five key aspects: biomass pretreatment, catalytic pyrolysis, catalyst deactivation, machine learning applications, and industrial production. Pretreatment methods improve biomass quality and facilitate subsequent processing. Catalytic pyrolysis, employing catalysts such as alkaline earth metals, acidic sites, zeolites, and rare-earth metals, shows great potential for producing renewable fuels and chemicals. The review compares the performance of various catalysts and discusses their impact on bio-oil yield and quality. Additionally, it summarizes major causes of catalyst deactivation and emerging machine learning approaches for optimizing pyrolysis processes. Current industrial-scale biomass refining installations are also reviewed. Finally, a SWOT analysis is provided to evaluate the challenges and opportunities of biomass pyrolysis, along with future research priorities for industrial scaling. • Biomass characteristics and pretreatment methods before pyrolysis were outlined. • Four types of catalysts and the mechanism during biomass pyrolysis were classified. • Three main deactivation mechanisms: coking, sintering, and poisoning were analyzed. • The opportunities and challenges associated with machine learning were summarized. • Catalytic pyrolysis is an efficient approach for clean energy production.