Studies Of Catalytic Reactions For The Synthesis Of Rubber Antioxidants 4010NA And 4020 As Well As The Curing Agent M-xylylenediamine

Rubber antioxidants 4010NA(IPPD)and 4020(6PPD)are widely used all over the world due to their excellent aging resistances.In China,most 4010NA and 4020 are industrially produced using copper catalysts in fixed-bed reactors,having the problems of unsatisfactory selectivity and product quality.In this work,supported nickel catalysts were prepared and used for the catalytic hydrogenations of the condensed solutions of N-phenyl-p-phenylene diamine(PPD)with acetone(ACE)and 4-methyl-2-pentanone(MIBK),respectively,in a fixed-bed rector to produce IPPD and 6PPD.The operation conditions such as temperature,pressure,space velocity,hydrogen/PPD molar ratio were optimized.Some important results obtained are summarized below:(1)Condensation reaction of PPD with acetone occurred at room temperature,forming an imine product,N-isopropylidene-N'-phenyl-benzene-1,4-diamine.For the mixture containing 20%PPD and 80%acetone(mass percentage),the condensation reaction reached equilibrium in about 30 hours when the yield of imine reached about 47%.(2)Temperature and pressure were found to affect the conversion of PPD and selectivity to IPPD significantly from the hydrogenation of condensed solution of PPD with acetone.The catalyst Ni/MgAlO was found to be better than Ni/Al2O3 for the selectivity to IPPD,indicating the importance of surface basicity for the production of desired product IPPD.The reaction conditions were optimized as T=120?,P=4.0 MPa,nH2:nPPD=15:1 and WHSVPPD=0.5 h-1,at which the conversion of PPD reached 99.2%with 90.7%selectivity to IPPD.(3)Condensation reaction of PPD with MIBK could also take place at room temperature,generating N-(1,3-dimethyl-butylidene)-N'-phenyl-benzene-1,4-diamine,but in a significantly longer time(140 h)to reach the equilibrium.The yield of imine was determined to be about 45%after the equilibrium when the solution of 20%PPD-80%MIBK was used.(4)Temperature and space velocity were the two main factors affecting the hydrogenation of imine formed from the condensation of PPD with MIBK and the selectivity to 6PPD over the Ni/MgAlO catalyst.The reaction conditions were optimized as:T=150?,P=3.0 MPa,nH2:nPPD=15:1 and WHSVPPD=0.5 h-1,at which the conversion of PPD reached 57.8%and 83.5%selectivity to 6PPD.m-Xylylenediamine(MXDA)is an excellent curing agent of epoxy resin.In this work,the catalytic hydrogenation of isophthalonitrile(IPN)to MXDA was studied in a fixed-bed reactor using Ni/MgAlO catalysts.It was found that the addition of piperidine in the reaction feed increased the selectivity to MXDA.The reaction conditions were optimized as:T=100?,P=4.0 MPa nH2:nIPN=15:1 and WHSVIPN=0.5 h'1,at which the conversion of IPN reached 100%with 100%selectivity to MXDA when a mixture solution 10%IPN-20%piperidine-70%DMF was used as a feed.