Study On Catalytic Cracking And Post-treatment Of Phenol Tar

Phenolic tar usually refers to the by-products with high content of phenolic compounds produced by petrochemical and coking industries.In recent years,with the rapid increase of phenol production in China,the annual output of phenol tar has also increased.Phenol tar contains a large number of toxic substances,which is harmful to personal health and environmental protection,and also has certain value of resource recovery.Based on the analysis of basic properties of phenol tar,The distillation range is between 123.8℃-558.4℃,Among them,the fraction with boiling point less than 350℃is about 77-80%,It is the key point of phenol tar resource,The main substances include phenol,α-methyl styrene,acetophenone,α-methyl styrene dimer,4-kumbyl phenol,2-kumbyl phenol and so on.By simulated distillation,it is found that the fraction with boiling point greater than 350℃is not constant,According to the improved B-L law,The molecular weight in the recombination fraction is larger,High degree of condensation,H/C ratio less than 1.5,It belongs to heavy oil with poor quality.To realize the resource utilization of phenol tar,this paper studies the modification of phenol tar withγ-Al₂O₃as support and reagent A to prepare a BJYC solid base catalyst for catalytic cracking of phenol tar.Treatment of phenol tar by catalytic pyrolysis by vacuum distillation,The total yield reached 74.68%,At 200℃,0.005 Mpa Separation of phenol,α-methyl styrene,phenylacetone components.Then a solid base catalyst with a mass fraction of 5%was added,At 340℃,4 h.Response Compared with alkaline powder catalyst and metal sulfate catalyst,The solid alkali catalyst prepared in the experiment has higher performance,and can be reused.Can solve the problem of difficult separation ofα-methyl styrene dimer and withered phenols in phenol tar,and will not introduce alkali metals into the uncracked recombination.According to the structural characterization of the pyrolysis residue,the average molecular weight of the pyrolysis residue is obviously reduced compared with the recombination fraction before cracking,but it is still dominated by highly condensed heavy cyclic aromatics.It is still difficult to obtain high added value products by lightweighting.It is found that there are still toxic substances such as phenols in the pyrolysis residue by infrared spectroscopy.According to the analysis of the key parameters of solid waste treatment,such as calorific value,ash content,volatile content and metal ion content of pyrolysis residue,it is found that the calorific value in pyrolysis residue can be obtained by incineration,and it is an ideal reduction and harmless measure for producing acid gas and ash containing heavy metals.In addition,according to the judgment of the properties of cracking residue,it is also possible to try to treat the cracking residue by coking.