Ethoxylation and propoxylation reactions are performed in the industry to produce mainly non-ionic surfactants and ethylene oxide(EO)–propylene oxide(PO) copolymers.Both the reactions occur in gas–liquid reactors by...Ethoxylation and propoxylation reactions are performed in the industry to produce mainly non-ionic surfactants and ethylene oxide(EO)–propylene oxide(PO) copolymers.Both the reactions occur in gas–liquid reactors by feeding gaseous EO,PO or both into the reactor containing a solution of an alkaline catalyst(KOH or Na OH).Non-ionic surfactants are produced by using liquid starters like fatty alcohols,fatty acids or alkyl-phenols,while when the scope is to prepare EO–PO copolymers the starter can be a mono-or multi-functional alcohol of low molecular weight.Both reactions are strongly exothermic,and EO and PO,in some conditions,can give place to runaway and also to explosive side reactions.Therefore,the choice of a suitable reactor is a key factor for operating in safe conditions.A correct reactor design requires:(i) the knowledge of the kinetic laws governing the rates of the occurring reactions;(ii) the role of mass and heat transfer in affecting the reaction rate;(iii) the solubility of EO and PO in the reacting mixture with the non-ideality of the reacting solutions considered;(iv) the density of the reacting mixture.All these aspects have been studied by our research group for different starters of industrial interest,and the data collected by using semibatch well stirred laboratory reactors have been employed for the simulation of industrial reactors,in particular Gas–Liquid Spray Tower Loop Reactors.展开更多
Glycerol from biodiesel production can be an important industrial feedstock for chemical commodities as it can be used in the food,cosmetic,pharmaceutical and tobacco industries.However,crude glycerol derived from bio...Glycerol from biodiesel production can be an important industrial feedstock for chemical commodities as it can be used in the food,cosmetic,pharmaceutical and tobacco industries.However,crude glycerol derived from biodiesel production has a low value because of impurities.The purification of this glycerol into a high grade involves high costs and is not economically feasible for small and medium size plants.The glycerol conversion into chlorohydrins was studied using new homogeneous catalysts and hydrochloric acid as chlorination agent.This is an interesting alternative route to epichlorohydrin and then to epoxy resins.The behavior of two series of homologous catalysts,glycolic acid series(glycolic acid,di-glycolic acid and thio-glycolic acid) and amminoacid series(glutamic acid,aspartic acid and cysteine),were investigated for their activity and selectivity.Glycolic acids were more active than amminoacids.The pK_a values had a strong influence on selectivity(mono-chlorohydrins/di-chlorohydrins) for the amminoacid series,which was not observed for the glycolic acids.A kinetic model and reaction mechanism developed in a previous work were used for interpreting the kinetic runs.展开更多
文摘Ethoxylation and propoxylation reactions are performed in the industry to produce mainly non-ionic surfactants and ethylene oxide(EO)–propylene oxide(PO) copolymers.Both the reactions occur in gas–liquid reactors by feeding gaseous EO,PO or both into the reactor containing a solution of an alkaline catalyst(KOH or Na OH).Non-ionic surfactants are produced by using liquid starters like fatty alcohols,fatty acids or alkyl-phenols,while when the scope is to prepare EO–PO copolymers the starter can be a mono-or multi-functional alcohol of low molecular weight.Both reactions are strongly exothermic,and EO and PO,in some conditions,can give place to runaway and also to explosive side reactions.Therefore,the choice of a suitable reactor is a key factor for operating in safe conditions.A correct reactor design requires:(i) the knowledge of the kinetic laws governing the rates of the occurring reactions;(ii) the role of mass and heat transfer in affecting the reaction rate;(iii) the solubility of EO and PO in the reacting mixture with the non-ideality of the reacting solutions considered;(iv) the density of the reacting mixture.All these aspects have been studied by our research group for different starters of industrial interest,and the data collected by using semibatch well stirred laboratory reactors have been employed for the simulation of industrial reactors,in particular Gas–Liquid Spray Tower Loop Reactors.
文摘Glycerol from biodiesel production can be an important industrial feedstock for chemical commodities as it can be used in the food,cosmetic,pharmaceutical and tobacco industries.However,crude glycerol derived from biodiesel production has a low value because of impurities.The purification of this glycerol into a high grade involves high costs and is not economically feasible for small and medium size plants.The glycerol conversion into chlorohydrins was studied using new homogeneous catalysts and hydrochloric acid as chlorination agent.This is an interesting alternative route to epichlorohydrin and then to epoxy resins.The behavior of two series of homologous catalysts,glycolic acid series(glycolic acid,di-glycolic acid and thio-glycolic acid) and amminoacid series(glutamic acid,aspartic acid and cysteine),were investigated for their activity and selectivity.Glycolic acids were more active than amminoacids.The pK_a values had a strong influence on selectivity(mono-chlorohydrins/di-chlorohydrins) for the amminoacid series,which was not observed for the glycolic acids.A kinetic model and reaction mechanism developed in a previous work were used for interpreting the kinetic runs.
