Catalytic Oxidation Routes for Benzaldehyde Production: Synthesis Methodologies and Sustainability Challenges

Benzaldehyde is a key intermediate in the fine chemical, pharmaceutical, fragrance, and agrochemical industries, and the development of efficient and sustainable synthetic routes remains a major research priority. This review critically examines the principal catalytic pathways reported for benzaldehyde production, with particular emphasis on the oxidation of benzyl alcohol and the partial oxidation of toluene. Reaction conditions, catalytic systems, and performance descriptors such as conversion and selectivity are systematically analyzed, highlighting the strengths and limitations of each approach. Special attention is given to the choice of oxidants, reaction phase, and operating temperature, as these factors strongly influence process efficiency and product distribution. From a sustainability perspective, conventional routes are compared with greener alternatives based on molecular oxygen or air, aiming to reduce energy consumption and the generation of hazardous by-products. The review further discusses current challenges associated with catalyst stability, overoxidation, and process scalability. It identifies the principal scientific gaps limiting the industrial implementation of heterogeneous catalytic systems and critically examines how catalyst design, synthesis methodologies, sustainable feedstocks, waste-derived materials, and techno-economic considerations can collectively contribute to scalable and environmentally responsible benzaldehyde production. Finally, future research directions are proposed to guide the development of highly selective, economically viable, and sustainable catalytic processes.