**2. Biomass conversion reaction pathways**

In our analysis, seventeen different biomass materials were considered and information on the conversion of these biomass materials to known feedstock chemicals was derived from publications cited in this section.

Seventeen biomass sources, considered in this paper, are as follows:



The biomass conversion processes employed to convert these biomass sources to feedstock chemicals include pyrolysis, which is heating the biomass material, either in the presence of a catalyst, such as alumina, or noncatalytically. The flash pyrolysis process is conducted in an oxygen-free, inert gas atmosphere in the temperature range of 600–1000°C and 1 atmosphere pressure. Products of pyrolysis consist of gases, such as carbon monoxide, carbon dioxide, methane, etc., and liquids, such as heavier hydrocarbon oils and ammonia.

Another biomass conversion process used is hydrothermal liquefaction, where the biomass material, once shredded into small pieces, is heated in water under


#### **Table 1.**

*Biomass sources, composition and carbon economy.*

hydrothermal pressures and temperatures ranging from 500 to 700°C. This converts the biomass material into a liquid oil product, which is then processed as crude oil, using cracking and distillation.

Gasification of biomass under controlled oxidative conditions produces synthesis gas, which can be converted to chemicals using the well-known Fisher-Tropsch chemistry.

Hydrolysis, using acids, followed by fermentation converts biomass into chemicals, such as ethanol, acetic acid, etc. These chemicals become the feedstocks for a variety of industrial chemicals.

**Table 1** lists the chemical composition of the various biomass sources and their carbon economy [5–20].
