为开发高效、稳定且具有双功能酸性位点的碳基固体酸催化剂，推动纤维素水热转化制备糠醛工艺，以稻草秸秆（RBC）为碳基载体、FeCl3·6H2O和ZnCl2为活性金属盐，通过金属浸渍、高温炭化和浓硫酸磺化，制备了兼具Br?nsted和Lewis酸位点的固体酸催化剂，并将其用于催化纤维素水解制备糠醛。采用SEM、EDS、XRD、XPS、ICP-OES和Py-FTIR表征了催化剂，探究了金属负载量、负载比例、γ-戊内酯/水(GVL/H2O)溶剂体系、反应温度和反应时间对固体酸催化剂催化纤维素水解制备糠醛影响。结果表明，在总金属负载量相同的条件下，n(Fe3+)∶n(Zn2+)是调控L酸位点数量的关键因素。在Fe和Zn总负载量2%、n(Fe3+)∶n(Zn2+)＝1∶1的条件下，制备的固体酸催化剂SO42-/RBC500-Fe1-Zn1...

生物质能作为可再生能源,具有分布广泛、储量丰富及再生性强等一系列优点,并且,作为唯一的可再生碳质资源,生物质能具有生产热能、电能、燃料及高附加值化学品的巨大潜力。然而,通过常规热转化手段所制备的生物油,其普遍具有含氧量高、含氢量低及稳定性差等缺点,需进一步对热解油进行提质优化,以制备高品位的液体燃料。本文从多级孔道酸性分子筛催化剂改性,金属氧化物催化剂与分子筛协同催化,生物质与多氢原料在线催化重整,以及流化态下生物质的热解过程CFD数值模拟等角度出发,分别开展了分子筛催化剂的碱溶液-水热处理复合改性,介孔多元碱性金属氧化物催化剂的合成及其与HZSM-5分子筛的双级催化,生物质与多氢原料在流化床/固定床串联反应器中的双级催化重整等一系列基础研究。在分子筛催化剂孔道特性及酸性特征的优化方面,探索了碱溶液浸渍-水热处理复合改性HZSM-5分子筛的反应机制,并分别采用了废弃竹屑、废弃油脂等作为原料,通过热裂解-色谱/质谱联用仪（Py-GC/MS）,对复合改性的HZSM-5分子筛其催化性能进行了测试。试验结果表明,复合改性的时间由0增加至2h时,改性催化剂作用下废弃竹屑热解含氧类产物的相对含量逐渐下降,而芳香烃类产物的相对含量则由18.23%增加至31.88%,当复合改性处理的时间进一步延长至6h时,则造成了芳香烃含量的急剧下降。苯、甲苯、对甲苯（BTX）及萘等产物的相对含量,随复合改性处理时间的增加呈现先升高后降低变化,并且甲苯及对甲苯为主要的单环芳烃类物质。在介孔多元碱性金属氧化物催化剂的制备及其与酸性HZSM-5协同催化方面,首先以商业碱性金属氧化物MgO、CaO为催化剂,对比研究了金属氧化物与HZSM-5催化热解特性的异同,在此基础上,合成了介孔多元碱性金属氧化物催化剂,探索了其催化热解废弃竹屑制备酮类目标产物的性能,进一步分析了金属氧化物与酸性分子筛的协同催化机制,探究了金属氧化物与HZSM-5不同的反应模式对热解产物的影响。试验结果表明,MgO与HZSM-5双级催化热解系统中,随MgO占总催化剂比重的增加,芳香烃产物的相对含量先升高后降低,并且当其与HZSM-5的质量比为1:1时,芳香烃的相对含量达24.55%。当CaO与HZSM-5的质量比为1:1时,烃类产物（HCs）的相对含量亦达最大值22.77%,而不稳定、不利组分的含量被降至最低。合成的介孔多元碱性金属氧化物催化剂中,ZrO2-CeO2/γ-Al2O3作为催化剂的条件下,酮类、单环芳香烃类产物的相对含量达最高值,并且最大程度地抑制了酸类、重质酚类等非目标产物的生成。在其与HZSM-5组成的双级催化热解系统中,HZSM-5与ZrO2-CeO2/γ-Al2O3混合的催化模式工况下,单环芳烃的相对含量最高。在废弃竹屑与多氢原料的双级催化共热解方面,设计、搭建了串联的流化床与固定床双床热解-在线催化重整反应器,研究了催化重整反应温度对废弃竹屑热解产物分布的影响,探讨了废弃竹屑在原位及非原位催化两种不同模式下的热解特性,揭示了金属氧化物与HZSM-5的双级催化重整模式对芳烃类目标产物的作用机制,并进一步采用复合改性的HZSM-5为催化剂,分析了改性分子筛与MgO的双级催化重整对芳香烃类产物生成的影响。试验结果表明,废弃竹屑最佳的热解/催化重整温度为550℃/500℃。相对于MgO原位催化反应,其非原位工况下热解油的产率显著降低,并且呋喃类、烷氧基酚类的相对含量分别由22.35%、37.76%降低至12.95%、2.24%,而轻质烷基酚类的相对含量则由26.99%增加至62.38%。MgO与HZSM-5连续的催化模式最大程度地降低了酸类（2.44%）、呋喃类（10.87%）及酮类（4.51%）的相对含量,而极大地促进了芳烃类产物的生成（相对含量最大值:24.67%）。混合催化重整模式下,CaO与HZSM-5的双级催化重整使热解油中芳烃产物的相对含量达31.34%。废弃竹屑与废轮胎的共热解产物在HZSM-5及MgO连续催化重整工况下,HZSM-5/MgO质量比为2:3时芳香烃的相对含量最高;而混合的催化重整模式在HZSM-5/MgO质量比由1:4增加至3:2的工况下,比连续的双级催化模式更有助于促进BTX的生成。相对于未改性HZSM-5与MgO连续的双级催化重整模式,当分别采用碱溶液浸渍-水热处理复合改性2h、4h的HZSM-5,对废弃竹屑与废轮胎的共热解产物进行连续双级催化重整时,热解油的产率由29.71%分别提高至33.54%、32.73%,采用复合改性时间为2h（2AH-Z5）,对甲苯、甲苯的相对含量分别提高至26.66%、9.39%。在试验研究的基础上,对废弃竹屑在流化床内的热解过程进行了数值模拟研究。采用ANSYS数值模拟软件,结合生物质热解多步反应动力学模型,模拟了废弃竹屑的热解过程。结果表明,热解焦油及热解气的产率随反应温度由450℃增加至550℃逐步升高,550℃的热解温度可最大程度地提高热解油的产率。不同温度工况下热解三相产物产率的模拟值与试验值的偏差均在合理范围内,并且热解焦油在不同温度工况下其产率的模拟值均低于试验值。

This paper reports the results obtained for microwave-assisted catalytic fast pyrolysis (MACFP) of rice husk. The MACFP process employed a hierarchical catalyst prepared via a combination of organic alkali treatment (TPAOH) and the generation of an external layer of MCM-41-type mesoporous channels. We propose this catalyst which is used for the first time for pyrolysis of lignocellulosic biomass, as a tool to reduce coke agglomeration and increase hydrocarbon yields. Our results indicate that during catalyst preparation the mass fraction of cetyltrimethylammonium bromide (CTAB) has a direct effect on the content of MCM-41 formed on top of the HZSM-5 core. For MACFP, we hypothesize that the small molecules generated from thermal decomposition of rice husk react further to form aromatic and aliphatic hydrocarbons by decarbonylation, decarboxylation, oligomerization and aromatization. The highest hydrocarbon yield (60.5%) was obtained for a catalyst modified by a 2.0 mol/L TPAOH solution, with 10 wt% of CTAB (template for producing MCM-41), as well as with digestion and crystallization at 110 degrees C for 24 h. In addition, the highest liquid yield (47.6 wt%) was obtained at 550 degrees C. The relative content of hydrocarbons goes through a maximum of 60.5% with CTAB mass fraction which was higher than values obtained with MCM-41 (3.2%) and HZSM-5 (36.0%). Characterization and catalytic testing results suggest that the digestion temperature plays a more important role in the catalyst synthesis than the crystallization temperature. High digestion temperature (120 degrees C) decreases the overall hydrocarbon selectivity from 60.5% (110 degrees C) to 39.2%. The relative content of oxygenates reached the lowest value of 35.9% at the digestion and crystallization temperature of 110 degrees C. The synergistic effect of the MCM-41 shell and the HZSM-5 core promotes the catalytic activity, leading to outstanding deoxygenation capabilities and excellent selectivity to BTEX (52.7%). (C) 2020 Elsevier B.V. All rights reserved.

To obtain high-value bio-oil, pure ceria (CeO2) and a series of Ce/Fe composite metal oxides were synthesized via precipitation method and were used to enhance hydrocarbons and ketones production during catalytic pyrolysis of bamboo sawdust. The characterization results were comprehensively analyzed and revealed that doping CeO2 with Fe promoted the formation of a solid solution structure, which further increased the surface area and number of oxygen vacancies of the catalyst for deoxygenation. Experimental consequences demonstrated that, compared to non-catalytic trial, the catalytic pyrolysis over CeO2 generated lower amounts of acids and aldehydes, and enhanced the conversion of large oxygenates to monofunctional hydrocarbon precursors via decarboxylation, deoxidation, and ketonization. The concentrations of hydrocarbons and ketones obtained over Ce/Fe catalysts were significantly higher than those obtained over CeO2, and that was attributed to the higher surface area and oxygen storage capacity of Ce/Fe catalysts. Particularly, the composite catalyst with the Ce/Fe molar ratio of 4 (Ce0.8Fe0.2) presented the most optimal deoxidation capacity in this study. The relative concentration of hydrocarbons generated over Ce0.8Fe0.2 was the highest, and monocyclic aromatics and short-chain aliphatic hydrocarbons accounted for 47.13% and 29.72%, respectively, of the total hydrocarbons. Simultaneously, the amount of ketones, the main hydrocarbon precursors, obtained over Ce0.8Fe0.2 was significantly higher than that obtained over CeO2, and the fraction of linear and cyclic ketones of the total ketones increased from 45.96% for the non-catalytic pyrolysis to 97.57%. This further confirmed that the mesoporous Ce/Fe composite catalysts efficiently catalyzed the aldol condensation and ketonization reactions.

To improve the efficiency of the catalyst fast pyrolysis (CFP) of rice husk and the quality of bio-oil, we integrate both microwave heating and fluidized bed reactor methods and build a microwave-heated fluidized bed system. In this study, the liquid yield from the CFP of rice husk in a microwave-heated fluidized bed (55.3 wt.%) is significantly higher than that obtained from a fixed bed (47.6 wt.%). Meanwhile, the relative content of hydrocarbons from microwave assisted catalytic fast pyrolysis (MACFP) of rice husk (RH) over a hierarchical micromesoporous composite molecular sieve (HM-2.0 T) is 67.6 % higher than that (51.6 %) of the organic base modified HZSM-5 (HT-2.0) and HZSM-5 (40.2 %) in the microwave-heated fluidized bed system. Furthermore, we focused on the ratio of biomass to catalyst in CFP processing and discover that the increased amount of catalyst promoted the decarbonylation and decarboxylation reactions, producing more hydrocarbon compounds, however, the excessive amount of catalyst does not contribution to higher monocyclic aromatic hydrocarbon selectivity. Besides, the hierarchical micro-mesoporous composite catalyst had strong regeneration ability and reusability. The selectivity of monocyclic aromatics remained high when the regeneration times increase from 1 to 4, which provided possibilities for applications of hierarchical micro-mesoporous composite catalyst in industrial production in the future.

针对生物质热解制备所得生物油高氧含量、低热值等系列问题,提出金属类催化剂与复合分子筛HZSM-5/MCM-41（HM）协同催化的新方法。在Py-GC/MS热解仪以及催化热解重整系统上,采用单级和双级2种催化模式,考察不同金属类催化剂与HM对竹木屑热解产物分布的影响。实验结果表明:在单级催化模式下金属类催化剂有利于生物油含氧量的降低和品质的提高。在双级催化模式下引入HM,可进一步降低生物油的氧含量,同时显著提高烃类收率,最高达66.11%,单环芳烃选择性达66.87%。此外,在催化热解重整实验中发现Fe的添加可增强HM的芳构化能力,进一步降低酸醛酮等不利组分的相对含量,促进低聚物的二次裂解,提高单环芳烃的选择性,得到40.25%的最高烃类产率,协同效果更明显,具有很好的应用前景。

In this paper, flow and heat transfer of coal and biomass pellet were studied with discrete element method-computational fluid dynamics (DEM-CFD). Three-dimensional numerical simulation was applied and the modified DEM-CFD coupled with heating transfer model matches heating process well in fluidized bed. Properties of binary particles (coal and biomass pellet) in heating process were revealed by particle temperature, mixing index and heat transfer. Cylindrical biomass pellets exist in broader regions, and the desired fluidization state is obtained. The temperature of biomass pellet is 10-20 K lower than that of coal particles. Moreover, biomass addition can suppress temperature rise and aggravates the temperature contrast between biomass pellet and coal. In addition, cylindrical biomass pellets reduce the mixing index of binary particles. Vertical mixing index and horizontal mixing index decrease from 0.85 to 0.65 and 0.85 to 0.75, respectively. Gas-solid heat transfer and gas velocity in Z direction are obviously influenced by inlet air.

We performed microwave-assisted catalytic fast pyrolysis (MACFP) of rice husk (RH) over an alkali-treated HZSM-5 zeolite, for production of hydrocarbons. The treatment consisted in the modification of the HZSM-5 by the organic base tetrapropylammonium hydroxide (TPAOH) solution at several concentrations. We characterized the resulting catalysts by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption-desorption, and temperature-programmed sorption of ammonia (NH₃-TPD). The results suggest that the TPAOH treatment generated mesoporous structures in the HZSM-5, while preserving its microporous structure and crystallinity. We obtained the highest yield (45.9%) of hydrocarbons from MACFP of rice husk (RH) at 550 °C. As the TPAOH concentration increases, the relative content of BTEX hydrocarbons (benzene, toluene, ethylbenzene, and xylene) reaches a maximum value of 22.9% at 2.0 mol/L. A comparison of results obtained over the organic base TPAOH (HZSM-5 modified by 2.0 mol/L TPAOH solution) with those obtained over an inorganic base (HZSM-5 modified by 2.0 mol/L NaOH solution) shows a 4.3% increase in the relative content of monocyclic aromatic hydrocarbons for the TPAOH. In addition, the TPAOH-treated catalyst shows excellent selectivity of BTEX (58.5%), which is higher than the selectivity obtained with the parent HZSM-5 (51.2%) and NaOH-treated HZSM-5 (53.9%). The TPAOH-modified HZSM-5 catalyst effectively reduced coke formation by 4.6% compared to MACFP over the parent HZSM-5, most likely because TPAOH decreases the concentration of strong acidic sites on the outer surface of the catalyst, creating a mesoporous structure while retaining the weak acidic sites on the HZSM-5 inner surface. The new catalyst generated in this work contains a moderate amount of mesopores structures, which allows for effective upgrading of pyrolysis vapors while simultaneously reducing coke formation, thereby addressing a significant problem in the development of the catalytic fast pyrolysis process.
© 2019 Elsevier B.V.

Catalytic fast co-pyrolysis of waste greenhouse plastic films and rice husk over a hierarchical HZSM-5/MCM-41 catalyst was performed in an analytical Py-GC/MS. We evaluated the effect of pyrolysis temperature and the ratio of rice husk to waste greenhouse plastic films on the total peak area of condensable organic products and CO₂. In order to evaluate synergy possibilities among the two feedstocks, we performed non-catalytic pyrolysis and catalytic fast pyrolysis of rice husk and waste greenhouse plastic films separately. In addition, we report results for the catalytic fast co-pyrolysis of the mixture rice husk and waste greenhouse plastic films. The maximum relative content of hydrocarbons from catalytic fast co-pyrolysis of rice husk and waste greenhouse plastic films is obtained at 600 °C. When the mass ratio of rice husk to waste greenhouse plastic films is 1:1.5, the relative content of hydrocarbons reaches a maximum (71.1%). The hierarchical micro-mesoporous composite molecular sieve used in this work has outstanding catalytic activity and increases the relative content of hydrocarbons.
© 2019 Elsevier Ltd