Ruthenium Catalyzes The Hydroformylation Of Isobutylene To Produce Isovaleraldehyde

The hydroformylation of isobutylene catalyzed by rhodium phosphine catalyst is one of effective ways to synthesize isovaleric aldehyde.Isovaleric aldehyde is a kind of high value-added product,which is a commomly used edible spice.Besides,isovaleric acid,isoamyl amine,isovaleric acid ester compounds and other derivatives can also be used as the material of spices.In addition,isovaleric aldehyde is an important pharmaceutical intermediates,which can be used to further produce Vitamin E,pribaline and other drugs.And hydroformylation is an atom economy reaction,which means it can reasonably use olefins to make higher value products,so to synthesize isovaleric aldehyde economically and environmentally has an important commercial value to chemical industry.In this paper,several aspects had been studied in an intermittently stirred reactor,such as catalyst selection,condition optimization,impurity influence and stability study:1.Using dicarbony(2,4-pentanedionato)rhodium as the precursor of catalyst,we studied the catalytic reacivity of two ligands,triphenylphosphine and bisphosphite HY-P.It was found that the bisphosphite HY-P has a much better effect for hydroformylation of isobutylene,achieving high yield and selectivity,and L doesn't effect a lot.The optimal reaction conditions of the catalytic system are: reaction temperature is 110-120 ?,reaction pressure is 1.5 MPa,using isovaleric aldehyde as the solvent,isobutylene concentration is from 22.7% to 26.5%,rhodium concentration is 300 ppm,and the molar ratio between phosphine and rhodium is 2:1-4:1.In this condition,we got the best STY=3.47mol/(L*h),and the yield of isovaleric aldehyde is92%,the selectivity is nearly 98%.2.We focused on the influence of impurities in the system of isobutylene's hydroformylation reaction.We found that isovaleric alcohol in the products can react with isovaleric aldehyde,causing the decrease of yield and selectivity.Isovaleric acid effects a little,but it will destroy the stability of HY-P when it's mass is too much.And isobutane is an inert gas in this reaction.So we made a conclusion of the maximum mass ratio of these impurities to isobutene: isovaleric alcohol should be less than 1%,isovaleric acid shoud be less than 1%,and isobutane should not exceed 10%.In addition,this catalyst shows a good reactivityto 1-butene and 2-butene,so these butenes have no effect on the reaction of isobutylene,but butadiene will extend theinduction period,so the content of butadiene should be controlled strictly,and none of it is better.3.We made experiments to recycle the catalyst(rhodium/ bisphosphite HY-P /fertilizer L)in intermittent device.We found that the rhodium can not be out from the complex,and the ligand HY-P also does not decompose,which means the catalyst showed a good thermal stability.Moreover,the purity of the isovaleric aldehyde product obtained by distillation has achieved the technical grade standard,and it is much higher than it,providing a reliable guarantee for industrial production.