Synthesis, Characteirzation And Performance Of Solid Acid For MDA With Aniline And Phenol

Abstract：Methylenedianiline (MDA) is an important material for the production ofmethylene diphenyl for polyurethane synthesis. The industrial production of MDA iscurrently performed by the reaction of formaldehyde with aniline in presence ofalmost stoichiometric amounts of HCl. As MDA is yielded in the hydrochloride form,it has to be neutralized with NaOH prior MDI. HCl is actually spent in stoichiometricamounts and a large amount of waste containing NaCl contaminated with aniline iscreated.Therefore, it is of great interest to replace the mineral acid in the process by asolid acid catalyst. Not only simplify the process, but also decrease the amount ofresidual water. In this paper, three kinds solid acids: sulfated mesoporous zirconia、zeolites and Meso-microporous composite molecular sieve were prepared and used insynthesis MDA with aniline and phenol in order to explore a feasible path to greensynthesis MDA. Research work carried on in this thesis can be divided into threeparts:(1) Sulfated mesoporous zirconia were synthesized by the in-situ one-potsynthesis, and using triblock copolymer P123as template, zirconium isopropoxide aszirconium source, sulfate as sulfiding agent.The effect of amount of sulfur andcalcinated temperature to superacids structures were inverstignted. The resultsshowed that sulfur could expand pore channel. The ordered mesostructure couldmaintained in appropriate additive sulfur (0.4ml) and calcinated temperature (650℃).The optimum synthesis conditions of MDA using sulfated mesoporous zirconiaas catalyst were: the reaction time150℃, reaction time1.5h, additive sulfur0.4ml,calcinated temperature450℃.(2) Four kinds of zeolites, ZSM-5、mordenite、Y and Beta, which with differentstructure were used to synthesis MDA with aniline and phenol. The results showedthat the yield of MDA increased with increasing of pore diameter. The selectivity of2,4’-MDA were depended on external acid amount of zeolites, however selectivity of4,4’-MDA activity were depended on internal acid amount of zeolites. Steam treatment was applied to modify Y to obtain USY. The result showed thatUSY zeolite had a bigger pore diameter than Y. At the same time, it should higherconversion than Y for its bigger diameter.The effect of Si/Al ratio of ZSM-5on synthesis of MDA by adjusting aluminumcontents was investigated. With the decrease of Si/Al ratio, the yield of MDAincreased.(3) Meso-microporous composite molecular sieve with two-dimensionalhexagonal mesoporous structure and MFI microporous structure was synthesized byusing carbon-silica composites as silica resource in various carbon/silica ratios,TPAOH as microporous structure directing agent.The carbon-silica composites structure effect by the calcinated temperature. Thepore structure of carbon-silica composites tended to inkbottle type cage-like pore atlow calcinated temperature. However, the pore tended to column pore and porediameter shrink at high calcinated temperature.Sample with appropriate carbon content order structure and the MFI-typemicoporous structure. The high content of carbon (above50%) would distructured thecrystallization of ZSM-5. Howerer, the low content of carbon (below20%), thismeans the high content of silica would destroy the ordered mesostructure.The BET surface areas of Meso-microporous composite molecular sieves werehigher than carbon-silica composites. When the ratio of carbon to silica was1.2, themesopore pore volume of molecular sieves increased from0.36cm~3/g to0.48cm~3/g.The synthesis conditions of MDA using C-ZSM-5-x-800as catalysts showedhigher conversion than the carbon-silica composites.