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Catalytic fast pyrolysis of cellulose in a microreactor system using hierarchical zsm-5 zeolites treated with various alkalis
Applied Catalysis A: General ( IF 5.5 ) Pub Date : 2017-08-12 , DOI: 10.1016/j.apcata.2017.07.034
Kai Qiao , Xu Shi , Feng Zhou , Hao Chen , Jie Fu , Huixia Ma , He Huang

Hierarchical ZSM-5 catalysts were prepared by desilication using NaOH, Na2CO3 and TPAOH with different concentrations under the same treatment conditions. Their structures and acidities were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption and desorption (N2-BET) and ammonia temperature-programmed desorption (NH3-TPD). The catalytic fast pyrolysis (CFP) of cellulose to produce aromatics over the hierarchical ZSM-5 catalysts prepared using different alkali treatments was investigated. The alkali treatment by Na2CO3 (0.4 ∼ 0.8 M) was much milder than treatment by NaOH, which allowed the desilication process to be highly controllable, resulting in an increase of both the amount and strength of the strong acid sites, and the formation of hierarchical structures combining micro- and mesoporosity. The organic hydroxide TPAOH did not change the pore structure of ZSM-5, but it greatly increased the relative crystallinity. The CFP of cellulose with HZSM-5 produced 35.5% liquid aromatic hydrocarbons and 32.7% coke. The yield of aromatics increased after Na2CO3 treatment but decreased after NaOH treatment. In addition, the yield of coke showed the opposite trend. The highest aromatic yield (38.2%) and lowest coke yield were obtained in the CFP of cellulose with the desilicated zeolite treated with 0.6 M Na2CO3. The increased acidity in hierarchical ZSM-5 treated with Na2CO3 increased the selectivity of highly valuable aromatics, such as benzene, toluene, and xylene, and decreased the selectivity of large aromatics. TPAOH-treated HZSM-5 showed a slightly increased yield of aromatics due to the repair effect of TPAOH, but this treatment did not form a mesoporous structure.



中文翻译:

在微反应器系统中使用经各种碱处理的分级zsm-5沸石在纤维素上催化快速热解纤维素

在相同的处理条件下,通过使用不同浓度的NaOH,Na 2 CO 3和TPAOH进行脱硅反应,制备了分级ZSM-5催化剂。通过X射线衍射(XRD),扫描电子显微镜(SEM),N 2吸附和脱附(N 2 -BET)和氨程序升温脱附(NH 3 -TPD)表征了它们的结构和酸度。研究了纤维素的催化快速热解(CFP)以在使用不同碱处理方法制备的分级ZSM-5催化剂上生产芳烃。Na 2 CO 3的碱处理(0.4〜0.8 M)比用NaOH处理要温和得多,这可以使脱硅过程得到高度控制,从而导致强酸位点的数量和强度均增加,并形成结合了微观结构和微观结构的层次结构。中孔性。有机氢氧化物TPAOH不会改变ZSM-5的孔结构,但会大大增加相对结晶度。用HZSM-5制成的纤维素CFP产生了35.5%的液态芳烃和32.7%的焦炭。Na 2 CO 3后芳香族化合物的产量增加处理,但经NaOH处理后下降。另外,焦炭的产量显示出相反的趋势。用0.6M Na 2 CO 3处理脱硅沸石的纤维素的CFP中获得最高的芳族产率(38.2%)和最低的焦炭产率。用Na 2 CO 3处理的分层ZSM-5中增加的酸度增加了高价值芳烃(如苯,甲苯和二甲苯)的选择性,并降低了大型芳烃的选择性。TPAOH处理的HZSM-5由于TPAOH的修复作用而显示出芳烃收率的略微提高,但该处理未形成中孔结构。

更新日期:2017-08-12
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