Production of renewable aromatics from tree-borne oils (TBO): Advances and future prospects

Aromatics are highly relevant petrochemical building blocks widely employed for the synthesis of many end-products. At present, aromatics are exclusively produced via catalytic or steam cracking of fossil-derived hydrocarbons having high carbon footprints. The alternative production of aromatics from biomass has been explored by different routes that are mainly multistep, including lignin depolymerisation followed by functionalisation or Diels − Alder reaction of sugars-derived furans and alkenes. Recently, tree-borne oils (TBO) showed exceptionally attractive features (liquid nature, high energy density, non-edible and abundantly available) as a feedstock to produce renewable aromatics under neat conditions. TBO is more selective towards the functionalised aromatics such as benzene, toluene, xylenes (BTX), ethyl benzene etc. Producing these aromatics from renewable sources is advantageous as the product can be purified using the current industrial setups without modifying existing infrastructure. The main objective of this review article is to provide an overview of current methods for producing renewable aromatic hydrocarbons from TBO’s. Special attentions are given to the characteristics of raw materials, the catalytic transformation of different types of TBO, reaction mechanism, and catalyst stability, as well as their specific challenges and opportunities.