1 reply to this topic

[GmanGura]

Is anybody aware of a situation where you can have more CO2 than CO in pyrolysis of biomass  at 1100 oC?

[Dacs]

It's hard to say. Gasification is a complex process, involving numerous reactions affected by kinetics and thermodynamics.

 

For CO2 and CO, there are three competing reactions that you have to look at:

1. Complete combustion of biomass, producing CO2. Mainly driven by reaction kinetics

2. Incomplete combustion of biomass, producing CO. Same as #1, by reaction kinetcs

3. Water-Gas Shift Reaction, involving both CO and CO2. Driven by thermodynamics

 

Excess O2 favors #1. Lack of O2 drives #2. Temperature drives #3 (along with presence of water).

 

I find 1100°C a bit low for gasification. With this temperature, CO2 formation is favorable.

 

Will it exceed CO though? My gut feel is no. Assuming you're producing syngas from pyrolysis, the intent is to produce H2 and CO mainly, so the gasifier reactor is not rigged to produce CO2 to begin with. O2 feed is controlled not to produce excess O2 in syngas, so the pyrolysis favors CO over CO2.

Edited by Dacs, 14 August 2024 - 12:30 AM.