Hi, I am Ranjeet Mishra from India. I want to know what exactly happens during formation of secondary cracking reaction during pyrolysis of biomass. is it possible by this reaction formation of phenol will be more?
Secondary cracking, at large, is quite a complex process, highly dependent on temperature, pressure, gas phase composition, and the presence of potentially catalytic surfaces, such as the reactor wall and coke. Another important variable is time.
Temperature acts on the rate of all reactions, and also on all kind of reaction equilibriums.
Pressure stimulates reactions of condensation, vacuum and very low pressure act to the opposite.
My experience is mainly in a range of 600-900 °C and I found it feasible to monitor primary as well as secondary reactions in cases such as propane and butane pyrolysis.
Obviously, biomass pyrolysis is generally at much lower temperature. Products are more complex and diverse. Moreover, phenol and its derivatives are quite reactive, so - even if they form rapidly, their depletion could be even faster.
There is a large body of knowledge gathered on chlorophenols: in minutes these will dimerise to PCDD/F when a suitable contact is available.
I am afraid that there are barely good answers to your question, since its scope is quite vast and undefined.
http://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.6b00935?journalCode=enfuem
http://www.sciencedirect.com/science/article/pii/S0016236101000552
Though it is a component-wise pyrolysis paper but it could help you to analyse that what kind of products may appear in different stages. The feedstock is vanillin. In tertiary stage, general appearance of products are the non-oxy 5-6 carbon membered rings, phenol, polymerizing components which help in coking, etc.
Further, this may also help you.
http://pubs.acs.org/doi/abs/10.1021/ef00002a001
Secondary cracking, at large, is quite a complex process, highly dependent on temperature, pressure, gas phase composition, and the presence of potentially catalytic surfaces, such as the reactor wall and coke. Another important variable is time.
Temperature acts on the rate of all reactions, and also on all kind of reaction equilibriums.
Pressure stimulates reactions of condensation, vacuum and very low pressure act to the opposite.
My experience is mainly in a range of 600-900 °C and I found it feasible to monitor primary as well as secondary reactions in cases such as propane and butane pyrolysis.
Obviously, biomass pyrolysis is generally at much lower temperature. Products are more complex and diverse. Moreover, phenol and its derivatives are quite reactive, so - even if they form rapidly, their depletion could be even faster.
There is a large body of knowledge gathered on chlorophenols: in minutes these will dimerise to PCDD/F when a suitable contact is available.
I am afraid that there are barely good answers to your question, since its scope is quite vast and undefined.
Dear RANJEET KUMAR MISHRA,
I hope you are doing fine.
Please see the following publications of my group.
Article Catalytic Pyrolysis of Plastic Waste: A Review
Article Influence of temperature and reaction time on the conversion...
Chapter The Energy and Value-Added Products from Pyrolysis of Waste Plastics
Article Effect of advanced catalysts on tire waste pyrolysis oil
I hope you will find them interetsing and relevant to your question.
With regards,
Nizami
Pyrolysis of solid fuels includes two main steps: primary and secondary pyrolysis. In primary pyrolysis, the solid fuel degrades into volatile gases and char. The primary pyrolysis products of solid fuels are non-condensable (light) gases (e.g., CO, CO2, H2O, and H2), light hydrocarbons (e.g., CH4, C2H4), condensable gases (tars), solid residue (char), and mineral ash. If the products of primary pyrolysis undergo further reactions at higher temperatures and longer residence times, it is known as secondary pyrolysis. Secondary pyrolysis includes processes such as cracking, polymerization, condensation, and carbon deposition, which can occur either homogeneously (when reactants are in the gas phase), or heterogeneously (when the reactions occur at the surface of a solid fuel or char particle). Secondary pyrolysis is not as widely studied as primary pyrolysis, but some secondary reactions, such as tar cracking, can have significant effects on the distribution of products. During secondary pyrolysis, the primary tars undergo seconcary reactions and either decompose to lighter gases or polymerize to form heavier hydrocarbons. Distribution of volatile species, depends on heating rate, temperature, fuel type, etc.
Reference: Article Characterization of pyrolysis products from fast pyrolysis o...
- Badges
- Science topic
- Similar topics
- Geoscience
- Asia
- India