BIOBTX

BTX is an acronym that stands for Benzene, Toluene and Xylene. Bio-BTX is BTX produced from biomass. The molecules are identical to the BTX from fossil energy sources, but made from biogenic feedstock. BioBTX therefore can be used in (drop-in) existing petro-chemical processes and downstream applications, but with the favorable CO2 footprint related to the biogenic feedstock. BioBTX can thus significantly contribute to the transition to a “greener” chemical industry.

Biomass, unlike coal, oil or natural gas, is the only renewable source of carbon, and it can be converted into energy, fuels and chemicals via different processes, either biochemical or thermochemical. Biochemical processes include e.g. digestion and fermentation, whereas thermochemical processes encompass pyrolysis, combustion and gasification.

Gasification is a thermochemical process in which a solid carbonaceous fuel (e.g. coal, biomass, or waste) is converted into a combustible gas called producer gas or syngas under sub-oxidizing conditions and medium-high temperatures (700-1200°C). The producer gas, in turn, is a versatile energy carrier which, after proper cleaning and upgrading, can be used in a number of applications: production of heat/power/mechanical energy, or feedstock for synthesis/recovery of fuels and chemicals.

Producer gas from gasification of wood and other lignin-rich feedstock contains significant concentrations of high-value compounds such as BTX (benzene, toluene, and xylenes) and ethylene. Ethylene and benzene make only a small part of the total volume of producer gas (~ 5% vol.), but in terms of energy, they contribute to a significant extent (~25% energy content). These compounds not only have a detrimental effect on the methanation catalysts (e.g. in an SNG production process), but they also have a higher economic value than the main product, SNG. Thus, the separation and recovery of benzene and ethylene from producer gas is a promising option that opens the way for the co-production of fuels and green chemicals from biomass gasification by reducing the production cost of biofuels.

ECN has been working in the last years in the development of technology and processes for the capture and recovery of these valuable compounds from producer gas instead of its (costly) conversion to syngas.

The process developed by ECN for the production of BTX from biomass or waste is composed of 3 parts:

  • Indirect gasification of the solid biomass/waste to producer gas using the MILENA technology.
  • Removal of polyaromatic hydrocarbons (PAH’s) from the producer gas using OLGA technology.
  • Harvest of bioBTX fraction using a BTX scrubber.
  • Production of synthetic natural gas (SNG) from the rest of producer gas using ESME technology.