摘要
制备了γ-Al2O3、HZSM-5、SnOPO4、SnZrOPO4(1:1)、SO42-/ZrO25种不同的固体酸催化剂,采用NH3程序升温脱附、吡啶原位吸附红外对催化剂进行了表征。考察了固体酸催化果糖在甲醇中转化的催化性能,结果表明,果糖的转化率均高于98%,产物分布与固体酸表面L酸、B酸酸量具有显著的相关性,乳酸甲酯的收率随着L酸量的减少而降低,L酸催化剂γ-Al2O3催化,主产物只有乳酸甲酯,收率为24.4%。而L酸位和B酸位共存的固体酸,产物中有乳酸甲酯、乙酰丙酸甲酯,并且乙酰丙酸甲酯的收率随着B酸量的增多而升高。最后考察了典型L酸γ-Al2O3及B酸L酸共存的固体酸HZSM-5不同反应时间的产物分布,结合气相-质谱联用对产物定性分析,得出了果糖转化过程L酸位催化和B酸位催化的反应路径。
Catalytic conversion of fructose directly into alkyl lactate is one of the effective ways for use of biomass to produce high value-added chemicals. Research shows that one of main factors influencing the alkyl lactate yield is Lewis and Bronsted acid sites on the surface of solid acid catalysts. A series of solid acid catalysts with different acid sites and concentration is prepared, including γ-Al2O3, HZSM-5 zeolite, SnOPO4, SnZrOPO4（1：1）, and SO4^2-/ZrO2. All of catalysts was characterized by using NH3 temperature-programmed desorption（NH3-TPD） and infrared spectroscopy with pyridine adsorption（Py-FTIR） techniques to figure out their total acid concentration, Lewis and Bronsted acid concentrations. The catalytic conversion of fructose in methanol over the five solid acid catalysts was studied. The results showed that the conversions of fructose can be higher than 98%; product distribution obtained depends greatly on Lewis and Bronsted acid amounts; and yield of methyl lactate lessened with the decrease of Lewis acid concentration. For γ-Al2O3 catalyst that contains only Lewis acid sites, the yields of methyl lactate achieved is 24.4%, while for these solid acid catalyst that contain both Lewis and Bronsted acid sites, the product obtained is not only methyl lactate but also methyl levulinate, and yield of methyl levulinate improves with increase of Bronsted acid concentration. Finally, the product distribution from the reactions catalyzed by typical Lewis acid solid catalyst γ-Al2O3 and HZSM-5 catalyst with both Bronsted and Lewis acid sites at different reaction time was investigated. Combined with the qualitative analysis obtained by gas chromatography-mass spectrometry（GC-MS）, the reaction pathway for fructose conversion catalyzed by Lewis and Bronsted acid sites was proposed.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2015年第9期3428-3436,共9页
CIESC Journal
基金
国家自然科学基金项目(21276191)~~
关键词
固体酸催化剂
果糖
乳酸甲酯
乙酰丙酸甲酯
B酸位
L酸位
solid acid catalyst
fructose
methyl lactate
methyl levulinate
Bronsted acid sites
Lewis acid sites
