/MxOy型固體超強酸催化劑改性研究進展

孫恩浩，劉　通，閆義彬，曹媛媛，蔣　巖，趙仲陽

(中國石油天然氣股份有限公司大慶化工研究中心，黑龍江 大慶 163714)

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綜述與展望

孫恩浩*，劉通，閆義彬，曹媛媛，蔣巖，趙仲陽

(中國石油天然氣股份有限公司大慶化工研究中心，黑龍江 大慶 163714)

摘要：介紹固體超強酸催化劑的發展、特點、應用及改性研究方向,研究催化劑酸強度低、催化劑易失活和穩定性差等問題,并提出解決方案。通過對國內外/MxOy型固體超強酸催化劑的研究，分析向載體中引入稀土元素、分子篩、其他金屬、納米材料和交聯劑對固體超強酸催化劑催化活性、熱穩定性、酸性、比表面積和晶型等的影響，綜述采用或硫酸鹽替換作為催化劑活性組分對催化劑的催化活性、酸強度及結構等的影響以及引入過渡金屬(貴金屬)形成的雙官能團對催化劑結構與活性的影響，對制約/MxOy型固體超強酸催化劑研究與工業化應用的催化劑壽命、穩定性、機械強度、合成方法、催化活性及催化劑再生等問題進行探討。

關鍵詞：催化劑工程；固體超強酸/MxOy型催化劑;改性

CLC number:TQ426.6;O643.36Document code: AArticle ID: 1008-1143(2016)05-0013-06

載體是構成催化劑的主要部分，是催化劑的骨架。通過優化載體，提高催化劑的比表面積，增加活性中心，可提高催化活性。對載體進行改性以增強催化劑的抗失活能力和機械強度，延長催化劑使用壽命。向催化劑載體中引入新元素也具有催化作用，可進一步提高催化劑活性[8-9]。

1.1稀土元素的引入

1.2分子篩的引入

提高催化劑的酸密度和酸強度可以提高催化劑的催化活性，而增大催化劑的比表面積是普遍采用的改性方法。分子篩是一種介孔型催化劑，由于比表面積大、孔徑可調、內晶表面極化度高、吸附能力強且介孔材料可阻止晶粒長大，形成有利于催化反應的四方晶相結構[12]，成為負載型催化劑的優良載體。

Wang J A等[13]制備了Pt/H3PW12O40/Zr-MCM-41催化劑，比表面積(359.3～549.2) m2·g-1，酸性中心數量(360～481) μmol·g-1，表明催化劑酸性很強，催化劑活性非常高，催化劑在低溫反應時，選擇性接近100%，在最適宜反應溫度(280～300)℃，選擇性約90%。Brito A等[14]分別以絲光沸石和ZSM-5合成了固體超強酸催化劑，研究表明，提高比表面積可以提高催化劑的酸強度，并且有金屬骨架制備的載體可以更好的發揮協同作用使B酸受L酸影響而加強，與李三喜等[15]結論一致。

1.3其他載體金屬元素的引入

1.4納米材料的引入

1.5交聯劑的引入

交聯黏土是一種多微孔型材料，可通過金屬氧化物(如Al2O3、ZrO2等)或復合金屬氧化物(如Al2O3-Ga2O3等)進行合成，該合成物質具有較大的比表面積，在(500～700)℃穩定性很好，由于交聯黏土本身具有一定量的酸性，且對以酸性中心為活性的反應有加強作用，適用于異構化反應和加氫裂解反應。Rachid Issaadi等[24]用蒙脫土(M)、鋯(Zr)和硫酸(S)合成了Zr-MS并負載Pd，制備Pd/Zr-MS催化劑，Zr-M的比表面積為247 m2·g-1，未復合Zr黏土的BET比表面積為95 m2·g-1，表明合成的載體具有更好的比表面積，可以提供更多催化活性吸附位。浸漬硫酸負載酸性組分的過程，使催化劑具有催化活性，但催化劑的孔結構被改變，比表面積減至135 m2·g-1，孔容增大，并得到較好的酸強度。以異丙醇脫水反應為探針，丙烷的最初生成速率為16×105mol·(s·g)-1，然后逐漸降低75%的速率，這是由于催化劑表面積炭覆蓋了活性中心，降低了催化活性，需要對催化劑進行再生。

2活性組分的改性

固體超強酸催化劑的活性組分為酸性中心，通過催化劑中L酸和B酸以協同的方式表現出來，以異構化為例，酸性中心可以催化正構烷烴重排異構化為異構烷烴，酸強度在一定程度上決定了催化劑的催化活性，故采用酸強度高和穩定性好的酸性組分對催化劑進行改性，制得高活性催化劑。

3過渡金屬的引入

4結語與展望

今后的研究方向為：(1) 催化劑機械強度研究，可以減少催化劑的孔道塌陷和孔道堵塞，延長其使用壽命；(2) 催化劑合成方法研究，提高催化劑的制備效率和比表面積，改善催化劑的結構，從綠色化工角度優化催化活性；(3) 解決催化劑的再生循環問題，提高催化劑再生后的催化效率，實現催化劑的重復利用。

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Sun Enhao*, Liu Tong, Yan Yibin, Cao Yuanyuan, Jiang Yan, Zhao Zhongyang

(Daqing Petrochemical Research Center of PetroChina, Daqing 163714, Heilongjiang, China)

Abstract:The development,characteristics,application and modification of solid superacid catalysts were introduced.The existing problems of low acid strength,easy deactivation and poor stability of the catalysts,etc. were investigated,and the solutions were put forward.Through the research of domestic and international /MxOy solid superacid catalysts,the effects of rare earth element introduction,molecular sieves,other carrier metals,nano materials,and crosslinking agents on catalytic activity,thermal stability,acidity,surface area and crystal type of solid superacid catalysts were analyzed.Substituting or sulfate for ,the influence of or sulfate as the activity components of the catalysts on catalytic activity,acid strength and structure of the catalysts,and the effects of the introduction of transition metals (precious metals) formed the bifunctional catalysts on structure and catalytic activity of the catalysts were reviewed.The problems such as catalyst life,stability,mechanical strength,synthesis methods,catalytic activity and catalyst regeneration,which restricted the research on and commercial application of solid superacid catalysts,were discussed.

Key words:catalyst engineering; solid superacid; /MxOy catalyst; modification

收稿日期：2015-11-03；修回日期：2016-03-29

作者簡介：孫恩浩,1989年生,男，黑龍江省大慶市人，碩士，工程師，研究方向為工業催化。

doi:10.3969/j.issn.1008-1143.2016.05.003 10.3969/j.issn.1008-1143.2016.05.003

中圖分類號：TQ426.6;O643.36

文獻標識碼：A

文章編號：1008-1143(2016)05-0013-06

通訊聯系人：孫恩浩。