TS-1微球的制備及其甲基氯丙烯環(huán)氧化催化性能的研究
發(fā)布時間：2018-10-09 07:23
【摘要】：以鈦硅分子篩為催化劑,催化甲基氯丙烯與雙氧水直接環(huán)氧化生產(chǎn)甲基環(huán)氧氯丙烷的方法是一種工藝流程短,對環(huán)境無污染的綠色化學(xué)過程。本文開展合成高活性、易分離、適合淤漿床反應(yīng)器的整體式TS-1微球分子篩,及其催化甲基氯丙烯環(huán)氧化生成甲基環(huán)氧氯丙烷性能的研究。探討TS-1微球的形成過程和液相氧化催化活性,進(jìn)一步研究其催化甲基氯丙烯生成環(huán)氧甲基氯丙烷反應(yīng)的最優(yōu)條件和再生過程。我們在常規(guī)合成TS-1的體系中加入三嵌段共聚物F127,通過分步晶化后實(shí)現(xiàn)TS-1納米粒子的聚集成球。通過調(diào)節(jié)F127加入量控制微球分子篩的大小,進(jìn)一步添加微量CTAB表面活性劑使得微球形貌更加均勻。在物料摩爾比為TEOS:TPAOH:TBOT:H2O:F127:CTAB= 1:0.18:0.033:13.2:0.0027:0.0032時,合成的TS-1分子篩微球直徑為15 μm左右,形貌均勻。通過氮?dú)馕摳奖碚?發(fā)現(xiàn)TS-1微球與常規(guī)TS-1相比,比表面積增加,并形成了晶粒間介孔。在淤漿床中以TS-1微球催化H2O2氧化甲基氯丙烯生成甲基環(huán)氧氯丙烷,從工業(yè)化角度,考察了各個因素對雙氧水轉(zhuǎn)換率、甲基環(huán)氧氯丙烷選擇性和催化劑使用壽命的影響。在最佳反應(yīng)條件,即反應(yīng)溫度從313 K間斷升溫到343 K、MAC/H2O2摩爾比例為3、TBA/MAC質(zhì)量比為2、TS-1微球催化劑濃度為35 g L-1、NH3·H2O濃度為17 ppm、滯留時間為4 h時,催化劑壽命可以達(dá)到257 h,且此過程中甲基環(huán)氧氯丙烷選擇性高于95%,雙氧水利用率高于97%。在反應(yīng)過程中TS-1微球分子篩顯示出催化活性高和容易固液分離的特點(diǎn)。對TS-1微球催化H2O2氧化甲基氯丙烯生成甲基環(huán)氧氯丙烷的失活機(jī)理進(jìn)行了研究,發(fā)現(xiàn)失活主要是由于分子篩孔道內(nèi)積炭所致,伴隨著長時間反應(yīng)過程中分子篩內(nèi)部分骨架Ti的流失也是催化劑失活的原因。雙氧水洗滌與高溫焙燒都是催化劑再生的有效方法,隨著再生次數(shù)的增加,催化劑活性逐漸降低。
[Abstract]:The method of direct epoxidation of methoxypropylene and hydrogen peroxide to produce methyl epichlorohydrin using titanium-silicon molecular sieve as catalyst is a green chemical process with short technological process and no pollution to the environment. In this paper, the synthesis of monolithic TS-1 microsphere molecular sieve with high activity, easy separation and suitable for slurry reactor, and its catalytic properties of epoxidation of methyl chloropropene to methyl epichlorohydrin were studied. The formation process and the catalytic activity of liquid phase oxidation of TS-1 microspheres were discussed. The optimum conditions and regeneration process for the reaction of methylene to epichlorohydrin were studied. A triblock copolymer F127 was added to the system of conventional synthesis of TS-1, and the TS-1 nanoparticles were assembled into spheres by stepwise crystallization. By adjusting the amount of F127 to control the size of the microsphere molecular sieve, further adding a small amount of CTAB surfactants to make the morphology of the microspheres more uniform. At the molar ratio of TEOS:TPAOH:TBOT:H2O:F127:CTAB= 1: 0.18: 0.033: 13.2: 0.0027: 0.0032, the synthesized TS-1 molecular sieve microspheres are about 15 渭 m in diameter and uniform in morphology. It was found that the specific surface area of TS-1 microspheres was higher than that of conventional TS-1, and mesoporous grains formed. TS-1 microspheres were used to catalyze the oxidation of H2O2 to methoxychloropropane in slurry bed. From the point of view of industrialization, the effects of various factors on hydrogen peroxide conversion rate, selectivity of methyl epichlorohydrin and service life of catalyst were investigated. The optimum reaction conditions were as follows: the reaction temperature was increased from 313K to 343K / H _ 2O _ 2 molar ratio of 3o TBA / MAC was 2% TS-1 catalyst concentration was 35 g / L ~ (-1) NH _ 3H _ 2O concentration was 17 ppm, and the retention time was 4 h, when the catalyst concentration was 35 g / L ~ (-1) NH _ 3H _ 2O. The catalyst has a lifetime of 257 h, and the selectivity of methyl epichlorohydrin is higher than 95%, and the hydrogen peroxide utilization ratio is higher than 97%. TS-1 microsphere molecular sieves showed high catalytic activity and easy solid-liquid separation during the reaction. The deactivation mechanism of H2O2 oxidation of methoxypropylene to methoxychloropropane catalyzed by TS-1 microspheres was studied. It was found that the deactivation was mainly caused by carbon deposition in the pore channels of molecular sieve. The loss of part of skeleton Ti in molecular sieve was also the reason of catalyst deactivation. Hydrogen peroxide washing and high temperature roasting are effective methods for catalyst regeneration. With the increase of regeneration times, the activity of catalyst decreases gradually.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ223.26
本文編號：2258464
[Abstract]:The method of direct epoxidation of methoxypropylene and hydrogen peroxide to produce methyl epichlorohydrin using titanium-silicon molecular sieve as catalyst is a green chemical process with short technological process and no pollution to the environment. In this paper, the synthesis of monolithic TS-1 microsphere molecular sieve with high activity, easy separation and suitable for slurry reactor, and its catalytic properties of epoxidation of methyl chloropropene to methyl epichlorohydrin were studied. The formation process and the catalytic activity of liquid phase oxidation of TS-1 microspheres were discussed. The optimum conditions and regeneration process for the reaction of methylene to epichlorohydrin were studied. A triblock copolymer F127 was added to the system of conventional synthesis of TS-1, and the TS-1 nanoparticles were assembled into spheres by stepwise crystallization. By adjusting the amount of F127 to control the size of the microsphere molecular sieve, further adding a small amount of CTAB surfactants to make the morphology of the microspheres more uniform. At the molar ratio of TEOS:TPAOH:TBOT:H2O:F127:CTAB= 1: 0.18: 0.033: 13.2: 0.0027: 0.0032, the synthesized TS-1 molecular sieve microspheres are about 15 渭 m in diameter and uniform in morphology. It was found that the specific surface area of TS-1 microspheres was higher than that of conventional TS-1, and mesoporous grains formed. TS-1 microspheres were used to catalyze the oxidation of H2O2 to methoxychloropropane in slurry bed. From the point of view of industrialization, the effects of various factors on hydrogen peroxide conversion rate, selectivity of methyl epichlorohydrin and service life of catalyst were investigated. The optimum reaction conditions were as follows: the reaction temperature was increased from 313K to 343K / H _ 2O _ 2 molar ratio of 3o TBA / MAC was 2% TS-1 catalyst concentration was 35 g / L ~ (-1) NH _ 3H _ 2O concentration was 17 ppm, and the retention time was 4 h, when the catalyst concentration was 35 g / L ~ (-1) NH _ 3H _ 2O. The catalyst has a lifetime of 257 h, and the selectivity of methyl epichlorohydrin is higher than 95%, and the hydrogen peroxide utilization ratio is higher than 97%. TS-1 microsphere molecular sieves showed high catalytic activity and easy solid-liquid separation during the reaction. The deactivation mechanism of H2O2 oxidation of methoxypropylene to methoxychloropropane catalyzed by TS-1 microspheres was studied. It was found that the deactivation was mainly caused by carbon deposition in the pore channels of molecular sieve. The loss of part of skeleton Ti in molecular sieve was also the reason of catalyst deactivation. Hydrogen peroxide washing and high temperature roasting are effective methods for catalyst regeneration. With the increase of regeneration times, the activity of catalyst decreases gradually.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ223.26
【參考文獻(xiàn)】
相關(guān)博士學(xué)位論文 前1條
1 張海嬌;TS-1分子篩合成新方法及其催化性能的研究[D];華東師范大學(xué);2007年
，本文編號：2258464
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