Chemistry
The utilization of heavy fossil fuels or biomass rich in carbohydrates, (C6H10O5)n, for fuels or chemicals requires an initial thermochemical process called pyrolysis which fractures large polymers to mixtures of small volatile orgranic compounds (VOCs). A specific method of pyrolysis of biomass, termed "fast pyrolysis," converts particles of biomass to about 10% carbon-rich solid called char, about 15% gases such as carbon dioxide, and about 70% a mixture of organic compounds commonly referred to as "bio-oil" at 500 °C in 1–2 seconds.
Pyrolysis: Biomass + Heat → 0.70VOCs + 0.10Char + 0.15Gases
The volatile organics can be collected as a brown, highly acidic liquid for further thermochemical conversion by traditional processes such as steam reforming, gasification, catalytic partial oxidation, catalytic cracking, combustion, or hydrotreating.
Catalytic steam reforming: VOCs + H2O + Heat + Catalyst → H2 + CO + Catalyst
Catalytic partial oxidation: VOCs + O2 + Catalyst → H2 + CO + Heat + Catalyst
Catalytic combustion: VOCs + O2 + Catalyst → CO2 + H2O + Heat + Catalyst
These two sets of chemistries, pyrolysis and catalytic processing, are combined to form the reactive flash volatilization process. Solid hydrocarbons or biomass are contacted with high temperature (500–900 °C) catalysts to generate gases and volatile organic compounds. The volatile species flow into the catalyst with a reactant (H2, O2, or H2O) to convert to desirable products (H2, CO, H2O, CO2, or VOCs).
RFV: Biomass + heat + Reactant + Catalyst → Gases + VOCs + Reactant + Catalyst → Products + Catalyst
Read more about this topic: Reactive Flash Volatilization
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