磷鎢酸鹽催化選擇性氧化苯甲醇合成苯甲醛的研究*

楊 爽，劉 丹，桂建舟，高玉環(huán)，楊玉蓮，魯 鳳，廉金超

（遼寧石油化工大學(xué) 化學(xué)與材料科學(xué)學(xué)院，遼寧 撫順113001）

磷鎢酸鹽催化選擇性氧化苯甲醇合成苯甲醛的研究*

楊 爽，劉 丹，桂建舟**，高玉環(huán)，楊玉蓮，魯 鳳，廉金超

（遼寧石油化工大學(xué) 化學(xué)與材料科學(xué)學(xué)院，遼寧 撫順113001）

通過兩步法合成了兩種磷鎢酸鹽催化劑，并利用13CNMR、1HNMR、IR、XRD等技術(shù)對(duì)催化劑進(jìn)行了表征。表征結(jié)果顯示，磷鎢酸鹽均具有磷鎢酸的Keggin型結(jié)構(gòu)。將該催化劑用于催化氧化苯甲醇的反應(yīng)，以30%H2O2為氧化劑，分別考察了含不同陽離子的磷鎢酸鹽、反應(yīng)時(shí)間、反應(yīng)溫度、催化劑用量和H2O2用量對(duì)反應(yīng)的影響。結(jié)果表明，磷鎢酸鹽（[PyPS]3PW12O40）的催化效果較好，苯甲醇的轉(zhuǎn)化率77.69%，苯甲醛的選擇性91.52%。其最佳反應(yīng)條件為:n[PyPS]3PW12O40∶n(C6H5OH)∶n(H2O2)=1∶200∶600，溫度85℃，時(shí)間3h。反應(yīng)后催化劑易分離，重復(fù)使用4次后，苯甲醛轉(zhuǎn)化率仍為75.24%。

磷鎢酸鹽；催化氧化；苯甲醇；苯甲醛

Abstract:Two Keggin-type phosphotungstate catalysts were synthesized by a two-step method and characterized by13C NMR,1H NMR,IR and XRD.Their catalytic performances were evaluated by selective oxidation of benzoic alcohol to synthesize benzaldehyde in the presence of H2O2.The influence of different cations of the phosphotungstate,reaction time and temperature,the amount of catalyst and hydrogen peroxide on the catalytic activity had been studied.The phosphotungstate[PyPS]3PW12O40was found to exhibit higher catalytic activity.The optimum reaction conditions were as follows:n[PyPS]3PW12O40：n(C6H5OH)：n(H2O2)=1:200:600,reacting at 85℃ for 3h,the conversion of benzoic alcohol was 77.69%and the selectivity of benzaldehyde could reach 91.52%.After reaction,the catalyst could be separated easily by filtration,then washed with deionized water and dried under vacuum for the next run.There was no obvious change in the catalytic activity after recycling for 4 times.

Key words:Phosphotungstate;catalytic oxidation;benzoic alcohol;benzaldehyde

前 言

苯甲醛是一種重要的有機(jī)中間體和精細(xì)化工產(chǎn)品原料，廣泛應(yīng)用于香精、調(diào)料、醫(yī)藥和農(nóng)用化學(xué)品中[1]。苯甲醛傳統(tǒng)的生產(chǎn)方法是在有機(jī)體系中用錳、鉻的無機(jī)鹽做氧化劑將醇氧化。該方法存在耗能高、環(huán)境污染大等缺點(diǎn)，在錫改性MCM-48或鈦鎢改性HMS催化劑存在下，苯甲醇選擇性氧化成苯甲醛，但苯甲醇轉(zhuǎn)化率偏低[2～3]。因此尋找一種高效且環(huán)境友好的催化氧化反應(yīng)很有必要。

H2O2做為氧化合成反應(yīng)中理想的氧化劑，它的還原產(chǎn)物是水，易于處理，不會(huì)給環(huán)境帶來任何污染[4]，且相轉(zhuǎn)移催化技術(shù)(PTC)很好地解決了有機(jī)底物與H2O2不互溶的問題。……