物理化学学报
物理化學學報
물이화학학보
ACTA PHYSICO-CHIMICA SINICA
2013年
5期
1073-1079
,共7页
那银娜%刘民*%宋春山%郭新闻*
那銀娜%劉民*%宋春山%郭新聞*
나은나%류민*%송춘산%곽신문*
纳米HZSM-5%联苯%4-甲基联苯%水热处理%水
納米HZSM-5%聯苯%4-甲基聯苯%水熱處理%水
납미HZSM-5%련분%4-갑기련분%수열처리%수
Nano HZSM-5%Biphenyl%4-Methybiphenyl%Hydrothermal treatment%Water
以纳米HZSM-5(n(SiO2)/n(Al2O3)=26)分子筛为母体,采用水热处理、水热处理结合酸洗等方法对其进行改性,并以联苯(BP)与甲醇的烷基化为探针反应,在固定床反应器上考察了反应体系中生成的水及通入的水对改性HZSM-5催化性能的影响,并通过吡啶吸附傅里叶变换红外(FTIR)光谱、热重(TG)分析对改性前后样品的酸性及反应后样品积炭量进行了表征.结果表明,水热处理及水热处理结合酸洗都提高了催化剂的稳定性,酸洗后效果更好.在改性的HZSM-5催化联苯甲基化反应体系中,不通水的条件下,联苯的转化率随时间呈抛物线变化;通水后,联苯转化率30 h内稳定在8.6%左右,4-甲基联苯(4-MBP)的选择性增加至约60%;通水条件下升高反应温度至500°C,联苯的转化率在反应30 h后达最高点,选择性稳定在58%左右.水的存在不仅改善了催化剂的活性及稳定性,还能提高对位选择性.
以納米HZSM-5(n(SiO2)/n(Al2O3)=26)分子篩為母體,採用水熱處理、水熱處理結閤痠洗等方法對其進行改性,併以聯苯(BP)與甲醇的烷基化為探針反應,在固定床反應器上攷察瞭反應體繫中生成的水及通入的水對改性HZSM-5催化性能的影響,併通過吡啶吸附傅裏葉變換紅外(FTIR)光譜、熱重(TG)分析對改性前後樣品的痠性及反應後樣品積炭量進行瞭錶徵.結果錶明,水熱處理及水熱處理結閤痠洗都提高瞭催化劑的穩定性,痠洗後效果更好.在改性的HZSM-5催化聯苯甲基化反應體繫中,不通水的條件下,聯苯的轉化率隨時間呈拋物線變化;通水後,聯苯轉化率30 h內穩定在8.6%左右,4-甲基聯苯(4-MBP)的選擇性增加至約60%;通水條件下升高反應溫度至500°C,聯苯的轉化率在反應30 h後達最高點,選擇性穩定在58%左右.水的存在不僅改善瞭催化劑的活性及穩定性,還能提高對位選擇性.
이납미HZSM-5(n(SiO2)/n(Al2O3)=26)분자사위모체,채용수열처리、수열처리결합산세등방법대기진행개성,병이련분(BP)여갑순적완기화위탐침반응,재고정상반응기상고찰료반응체계중생성적수급통입적수대개성HZSM-5최화성능적영향,병통과필정흡부부리협변환홍외(FTIR)광보、열중(TG)분석대개성전후양품적산성급반응후양품적탄량진행료표정.결과표명,수열처리급수열처리결합산세도제고료최화제적은정성,산세후효과경호.재개성적HZSM-5최화련분갑기화반응체계중,불통수적조건하,련분적전화솔수시간정포물선변화;통수후,련분전화솔30 h내은정재8.6%좌우,4-갑기련분(4-MBP)적선택성증가지약60%;통수조건하승고반응온도지500°C,련분적전화솔재반응30 h후체최고점,선택성은정재58%좌우.수적존재불부개선료최화제적활성급은정성,환능제고대위선택성.
Nanosized HZSM-5 (n(SiO2)/n(Al2O3)=26) samples were hydrothermal y treated with and without subsequent HNO3 leaching. The performance of the samples for the alkylation of biphenyl (BP) with methanol to 4-methylbiphenyl (4-MBP) under fixed-bed down-flow conditions was investigated. Characterization was conducted by the adsorption of pyridine using Fourier transform infrared (FTIR) spectroscopy and thermogravimetric (TG) analysis. The effect of water on the catalytic performance of modified HZSM-5 was investigated. Both hydrothermal and combined hydrothermal-HNO3 treatments improved catalytic stability, with the latter exhibiting better stability. Without the addition of water, BP conversion behavior resembled an open down parabolic vs reaction time over modified HZSM-5. However, this change disappeared upon the addition of water to the reaction system. Both catalytic stability and selectivity of 4-MBP were improved upon the addition of water. BP conversion after 30 h on stream was 8.6%, and the selectivity of 4-MBP was as high as about 60%. Elevating the reaction temperature to 500 °C in the presence of water led to increased BP conversion with time on stream up to 30 h, and the selectivity was stable at~58%. The activity and stability of HZSM-5 were improved, and para selectivity was enhanced with the addition of water.
