Polyethoxylation and polypropoxylation reactions：Kinetics,mass transfer and industrial reactor design

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.

Investigation of Propoxylation and Ethoxylation of 2-Ethylhexanol in the Presence of an Alkaline and DMC Type Catalyst at Initial Stages of the Syntheses

This paper reports the results of monopropoxylation and monoethoxylation of ethylhexyl alcohol performed in the presence of KOH and a DMC type catalyst, respectively. The existing differences are discussed in terms of kinetic performance of the syntheses, as well as the obtained products＇ compositions. The investigated DMC type catalyst showed 60 to 70 times as high conversion rates, narrower homolog distributions and higher selectivity, in comparison with KOH. Interpretation of the experimental results was performed using kinetic parameters of the WeibulI-Nycander-Gold model and the Natta Mantica relationships. In spite of any differences between the reactivity of the investigated catalysts and alkylene oxides, a significant contribution ofpolymerisation parallel to the target polyaddition was determined, absorbing a major part of the converted adducts, both in the presence of DMC and KOH.

Biobased Aromatic-Aliphatic Polyols by Thiol-Ene Reactions of Propoxylated Mercaptanized Cardanol

Aromatic-aliphatic polyols were obtained previously from the thiol-ene reactions of propoxylated cardanol with hydroxyalkyl mercaptans;these aromatic-aliphatic polyols were then utilized in the preparation of rigid polyurethane foams with excellent properties.The current work describes a variant of cardanol polyol synthesis by thiol-ene reactions in three steps.The first step is propoxylation of cardanol by reacting cardanol with propylene oxide;the second step is mercaptanization of propoxylated cardanol by reacting double bonds with hydrogen sulfide;and the third step involves the addition of the thiol groups of mercaptanized propoxylated cardanol to the double bonds of allyl alcohol,glycerol-1-allyl ether,and trimethylolpropane allyl ether.Thus,obtained polyols were characterized by standard analytical methods.Rigid polyurethane foams prepared from these polyols show promising physical-mechanical properties.The rigid polyurethane foams can be used for various applications such as thermo-insulation of freezers,storage tanks and pipes for food and chemical industries,wood substitutes and flotation materials.