Study On Ammonolysis Technology Of Poly(3-hydroxybutyrate)

Poly(3-hydroxybutyrate)(PHB)is a kind of energy and carbon storage ester polymer in microorganism,which has the characteristics of green regeneration and biodegradation.Currently,PHB is commonly used in biodegradable biomaterials,such as being considered an ideal alternative to "white plastics".Different from traditional recycling methods,this paper proposes to convert PHB into high-value 3-aminobutyric acid and pyridine compounds to realize the high-value utilization of PHB to fine chemicals.As important raw materials and key intermediates for organic synthesis,3-aminobutyric acid and pyridine compounds are widely used in the fields of medicine,agriculture,industry,and food.There are two parts in this paper,which are two-step PHB synthesis of 3-aminobutyric acid and one-step PHB synthesis of pyridine compounds.Crotonic acid is the key intermediate in two-step ammonolysis.Among them,the first step of the reaction is to develop a new process for preparing crotonic acid by using low-carbon saturated hydrocarbons as solvents and non-catalytic pyrolysis of PHB.The study revealed the influence of different influencing factors(such as temperature,time,and different low-carbon saturated hydrocarbon solvents,etc.)on the yield of crotonic acid,and found that under the optimal process conditions(using cyclohexane as the solvent,210 ?,5 h)The yield of crotonic acid is as high as 89%.In contrast,the yield of crotonic acid under solvent-free conditions is only 77%,which fully shows that low-carbon saturated hydrocarbon solvent is beneficial to improve the yield of crotonic acid.The second step of the reaction process is to use crotonic acid as a raw material to carry out the addition reaction of the crotonic acid double bond amino group to prepare 3-aminobutyric acid.The second step is to prepare 3-aminobutyric acid by amino addition of crotonic acid double bond.It was found that the yield of 3-aminobutyric acid increased with the increase of reaction temperature,reaction time and ammonia content.Previous studies found that the ammonolysis of PHB in aqueous solution produced 3-hydroxybutyric acid and3-aminobutyric acid,in which the presence of water was the key factor for PHB to produce 3-hydroxybutyric acid.To avoid the influence of water on the product distribution,the one-step ammonolysis of PHB was carried out in alcohol solvent(such as methanol)system.It was initially found that pyridine compounds were the main products,and the reaction process conditions were further analyzed.The influence of the yield of pyridine compounds.In this project,there are two methods to solve the problem of PHB recovery.One is the combination of two-step ammonolysis technology to realize the transformation of PHB into high-value fine chemical 3-aminobutyric acid,which has important practical application prospects.The second is to establish a one-step ammonolysis of PHB to prepare pyridine compounds with methanol as solvent,which provides ideas for the development of efficient and selective preparation of target pyridine compounds with PHB in the future.This field will also be the focus of further research in the future.