Fabrication of a nano-sized ZSM-5 zeolite with intercrystalline mesopores for conversion of methanol to gasoline

Carbon deposition during methanol to hydrocarbons leads to the quick deactivation of ZSM-5 catalyst and it is one of the major problems for this technology. Decreasing the crystal size or introducing mesopores into ZSM-5 zeolites can improve its diffusion property and decrease the coke formation. In this paper, nano-sized ZSM-5 zeolite with intercrystalline mesopores combining the mesoporous and nano sized structure was fabricated. For comparison, the mesoporous ZSM-5 and nano-sized ZSM-5 were also prepared. These catalyst samples were characterized by XRD, BET, NH3-TPD, TEM, Py-IR and TG techniques and used on the conversion of methanol to gasoline in a fixed-bed reactor at T=405 degrees C, WHSV =4.74 h(-1) and P=1.0 MPa. It was found that the external surface area of the nano-sized ZSM-5 zeolite with intercrystalline mesopores reached 104 m(2)/g, larger than that of mesoporous ZSM-5 (66 m(2)/g) and nano sized ZSM-5 (76 m(2)/g). Catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores was 93 h, which was only longer than that of mesoporous ZSM-5 (86 h), but shorter than that of nano sized ZSM-5 (104 h). Strong acidity promoted the coke formation and thus decreased the catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores though it presented large external surface that could improve the diffusion property. The special zeolite catalyst was further dealuminated to decrease the strong acidity. After this, its coke formation rate was slowed and catalytic lifetime was prolonged to 106 h because of the large external surface area and decreased weak acidity. This special structural zeolite is a potential catalyst for methanol to gasoline reaction. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Introduction of table sugar as a soft second template in ZSM-5 nanocatalyst and its effect on product distribution and catalyst lifetime in methanol to gasoline conversion

Methanol to gasoline reaction was investigated on two prepared ZSM-5 catalysts. The first one was a conventional catalyst denoted as ZSM-5（C） and the other was a hierarchical catalyst-ZSM-5（S） which was prepared by incorporation of table sugar in catalyst gel during the synthesis procedure. The catalysts were characterized by FTIR, XRD, FE-SEM, N2 adsorption-desorption, NH3-TPD and TGA analytical technics. The proposed material showed pore modification as well as acidity moderating properties in ZSM-5 catalyst. The methanol to gasoline reaction was conducted in a fixed bed reactor with a WHSV of 1.5 h-1.Methanol conversions, gasoline yield and selectivity in production for the synthesized catalysts were determined by gas chromatography method. The sugar modified catalyst converted more methanol than the conventional one and an enhancement in catalyst’s life time was observed. The selectivity to aromatics and durene were reduced compared to the conventional catalyst, so the gasoline quality was also further improved. The coking rate of catalysts was calculated employing TGA method. A reduction in coking rate and an increase in coke capacity of the modified catalyst were observed.

Study of methanol-to-gasoline process for production of gasoline from coal

The methanol-to-gasoline (MTG) process is an efficient way to produce liquidfuel. The academic basis of the coal-to-liquid process is described and two different synthesis processes are focused on: Fixed MTG process and Fluid Bed MTG process. Then,the superiority of the Fluid Bed MTG Process is pointed out relative to the Fixed MTGProcess. In addition, the development of the coal-to-liquid technique in China is brieflysummarized.

Facile One-Pot Synthesis of ZSM-5 Aggregates with Interand Intra-Crystalline Mesopores for Methanol to Gasoline Conversion

ZSM-5 aggregates consisting of superfine and hierarchical nanocrystals(combined with micropores and intra-crystalline mesopores) with an average size of 30 nm were prepared through one-pot synthesis with the assistance of anionic polyacrylamide(APAM). The resultant zeolites(AHN-ZSM-5) were characterized by XRD, ICP-OES, SEM, TEM, BET, NH_3-TPD, Py-IR, and TG analyses and evaluated in the methanol to gasoline(MTG) reaction. Characterization results show that the hierarchical ZSM-5 aggregates possessed two kinds of mesopores, namely inter-and intra-crystalline mesopores. The amount of APAM considerably influenced the mesoporosity and textural properties of AHN-ZSM-5 zeolites. With the addition of APAM in the synthesis, the AHN-ZSM-5 zeolites exhibited large mesopore volume, large external surface area, and appropriate acidity. When applied in the MTG reaction, AHN-ZSM-5 demonstrated a catalytic lifetime that was 1.6 times longer than that of conventional ZSM-5 synthesized in the absence of APAM.

A comparison of hydrocarbons emission from engine running 85￣＃gasoline and M－100 methanol fuel

Increasing global interest in methanoi fuel has led us to investigate the exhaust emissionsof its engine. Analysis of its inorganic and organic emissions. such as CO. NO_x and hydrocarbons(total HC) have been widely reported. This paper presents an analysis of more than 20 kinds ofhydrocarbons in the emissions obtained from a spark-ignition Shanghai car running 85# gasoline anda comparison with emission from a Santana test car running M-100 methanol fuel. A set ofenrichment method has also been described. Test results show that at the current stage of methanolengine development the concentration of individual hydrocarbon including some poisonous substancesis lower than those of normal gasoline engine.

Fenton试剂作为·OH引发剂的超细纳米ZSM-5分子筛的合成及其催化MTG反应性能

通过向合成ZSM-5分子筛的初始凝胶中加入Fenton试剂作为羟基自由基(·OH)引发剂,在90℃下合成了系列不同晶化时间的超细纳米ZSM-5分子筛(NZ5-Fx)。作为对比,采用传统模板法在170℃下晶化合成了纳米ZSM-5分子筛(NZ5-T)。采用XRD、SEM、TEM、N_(2)物理吸附、^(29)Si MAS NMR、^(27)Al MAS NMR、EPR、NH_(3)-TPD和Py-IR等方法对分子筛进行了表征,并研究了·OH的引入对所合成的NZ5-Fx系列ZSM-5分子筛的物化性质及甲醇制汽油(MTG)催化反应性能的影响。结果表明,与样品NZ5-T相比,·OH促进下低温合成的NZ5-Fx系列ZSM-5分子筛具有更小的晶粒尺寸、更大的介孔孔容,位于孔道交叉处的骨架Al原子所占的比例更高,而且具有更加温和的酸性,在催化MTG反应中表现出更异优的催化性能。以纳米ZSM-5分子筛样品NZ5-F12d为MTG反应的催化剂,甲醇转化率为96.2%时,汽油的选择性高达66.5%。

MTG生产过程模拟及能耗分析

使用Aspen Plus流程模拟软件,采用RKS-BM和NRTL相结合的物性模拟方法,对200 kt/a甲醇制汽油过程进行全流程模拟.模型计算中C6＋馏分采用68～201℃虚拟组分表示,考察了将甲醇转化为汽油（MTG）过程的最终产物分布、汽油收率、汽油性质以及装置能耗.计算结果表明,MTG最终的汽油收率不仅与反应器出口C5～C10组分收率有关,也和汽油的雷氏蒸气压（RVP）密切相关,与汽油组分中C4组分含量成正比.MTG过程的能耗主要是蒸汽和电的消耗,其中循环气压缩机的电耗占全装置能耗的40.2％.MTG工艺过程中可利用反应热产生中压蒸汽,不仅可回收MTG装置多余的热量,而且使整个装置的能耗大大降低.

碱处理浓度对预脱铝ZSM-5成孔过程及其MTG反应性能的影响

在80℃水浴条件下,对ZSM-5分子筛进行酸碱处理改性;重点考察了碱处理溶液浓度对酸预处理脱铝后ZSM-5分子筛微观结构及其催化甲醇制汽油(MTG)性能的影响。通过BET、XRD、FT-IR、NH3-TPD和TEM等手段对样品进行表征。结果表明,单独酸处理没有改变分子筛孔结构,单独碱处理产生了并不明显的介孔。酸预处理后再碱处理可促进介孔的产生,产生更为显著的介孔结构;而且随着碱处理强度的增加,分子筛样品的介孔/微孔比表面积比例和孔体积均先增大后降低。酸浓度2 mol·L-1,碱浓度0.4 mol·L-1条件处理得到的分子筛,介孔比表面积比例和孔容均达到最大,酸量和酸强度最低。在400℃,0.1 MPa,WHSV=2.1 h-1条件下,甲醇制汽油反应性能最佳:汽油收率由未改性时的30wt%提高到34wt%,寿命更是由16 h延长到135 h,芳烃含量由原来的73wt%降至20wt%。

甲醇制汽油（MTG）集总动力学模型

用Ｓｅｄｒａｎ￣［１］的模型，对甲醇在ＺＳＭ－５分子筛上转化制汽油过程进行了集总动力学研究。用单纯形法对实验数据进行回归分析，求出了动力学参数。将此动力学模型预测固定床反应结果，计算值与实测值相对平均误差小于２０％。

HZSM-5催化剂在MTG反应中的积炭失活

在固定床不锈钢反应器中进行了HZSM-5分子筛催化甲醇制汽油(MTG)反应的催化性能和失活实验。采用热重、X射线衍射、FT-IR、低温氮吸附-脱附、色谱-质谱联用仪等方法对催化剂进行了表征。结果表明,在反应进行到336 h时,甲醇转化率为40%,汽油收率低至12.6%,催化剂严重失活,但在700℃有氧再生后活性恢复,且保持了完整的MFI结构。积炭是催化剂失活的主要原因,大部分积炭沉积在分子筛微孔中,积炭物种主要是带有双键的聚合态化合物和稠环芳烃。

用改良MTG方法自合成气两步合成汽油催化剂的研究

研制出改良MTG两段法的两段催化剂。固定一段催化剂,对二段分子筛催化剂进行了评选对比和特性考察。研究了不同反应条件(温度、压力和空速)对自合成气合成汽油反应催化剂的活性,选择性以及尾气、油品组成等的影响。结果表明,所合成的新型分子筛催化剂具有活性高、选择性好、寿命长的特性。适当升高一段反应温度有利于二甲醚的生成和CO转化率的增加。二段反应温度的升高可促进C_5^+的生成。随着一段反应压力升高,CO转化率增加。空速明显影响CO转化率,加大空速有利于低碳烃的生成。

NMTG-100高活性甲醇制汽油催化剂反应性能

研究了以ZSM-5分子筛为主体的NMTG-100甲醇制汽油催化剂在不同应用工艺条件下的反应性能,考察催化剂的稳定性,并对催化剂的再生性能进行研究。结果表明,该催化剂通过优化工艺参数,可直接得到辛烷值为93.5、芳烃质量分数<50%和烯烃质量分数<10%的汽油产品,甲醇转化率>99%,可用于甲醇制汽油的工业生产,具有良好的工业化前景。

我国以煤炭为原料的MTG生产现状

随着经济的快速发展,我国对原油及石油产品的需求量与日俱增,能源安全问题越来越受到人们的关注。我国是一个多煤少油的国家,煤炭在一次能源中所占的比重很大,存在生态环境污染严重、能源结构不合理等诸多问题。采用MTG(甲醇制汽油)技术将煤炭转化为甲醇汽油等液体石油产品,不仅可以缓解原油及石油产品的供应压力,而且对调整我国的能源结构具有重要意义。介绍了我国能源生产及供给情况、以煤炭为原料生产液体燃料情况以及MTG工艺的开发情况,同时提出了一些建议。

轻汽油醚化装置工艺流程模拟

利用稳态流程模拟软件PRO/Ⅱ,对0.4 Mt/a轻汽油醚化装置主要工艺流程进行了系统的模拟计算,介绍了软件建模的热力学方法选择、重要设备的模块选择、工艺建模过程及其主要设置。模型验证结果表明,所建模型具有较高的准确性和适用性。为实现活性烯烃最大转化率,保证碳五组分质量,利用所建模型对醚化分馏塔甲醇加注量和回流比,甲醇回收单元萃取水量、循环甲醇中水含量及萃取水中甲醇含量等参数进行了优化。结果表明,醚化分馏塔甲醇加注量控制在进料甲醇量的8.8%,醚化分馏塔回流比控制在2.0,萃取水量控制在10~11t/h,萃取水中甲醇质量分数控制在0.04%,循环甲醇中水质量分数控制在0.016%为宜。

甲醇汽油添加剂的应用与研究

甲醇汽油是高效清洁的能源,甲醇汽油添加剂对于甲醇汽油的稳定性、动力性等有着很大的影响。本文对甲醇汽油添加剂的种类及作用进行了分析,对乳化剂、助溶剂以及复合添加剂的种类、配比进行了深入研究,并使用粒径分析法对其应用效果进行验证,为获得更加高效的甲醇汽油贡献力量。

甲醇汽油的性能及分层试验研究

为了深入了解甲醇汽油的特性,对甲醇汽油的相关研究与当前应用进行了简要分析,详细分析了甲醇汽油的理化性能、能量密度、技术指标以及对发动机动力性能的作用,总结了甲醇汽油的现存技术问题,并开展了甲醇汽油分层试验研究,为后续甲醇的进一步研究与应用奠定了一定的理论基础。

铈改性HZSM-5催化剂对MTG反应的影响

在HZSM-5中引入金属元素进行改性,可以改变催化剂的酸性和孔结构,进而提高催化剂的抗积炭能力和选择性。选用金属铈改性前后的HZSM-5分子筛催化剂,在内径为16 mm的不锈钢管式反应器中考察反应温度、系统压力等条件对甲醇制汽油(MTG)反应的影响,并结合X射线衍射、FT-IR、低温氮吸附-脱附等对HZSM-5催化剂进行表征,分析了汽油收率、产物分布和产物组成的变化规律。结果表明,经铈改性后HZSM-5催化剂仍能保持完整的MFI结构,L酸强度增加。在反应温度为375℃,系统压力为2.0 MPa,进料空速为1.0 h^(-1)的条件下,甲醇转化率为100%,汽油的收率可达34%以上,反应效果和活性周期明显优于改性前。

MTO与FCC汽油降烯烃组合反应催化剂的研究

以甲醇制烯烃(MTO)与催化裂化(FCC)汽油降烯烃组合反应工艺为研究目标,采用分子筛催化剂,在小型固定床微型反应装置,研究MTO反应、汽油降烯烃反应以及甲醇与汽油混合炼制反应,比较了典型酸性分子筛催化剂的催化性能。结果表明,组合反应过程呈现出非稳态特征,小分子烯烃具有自催化现象,导致产物组成分布随反应时间显著变化。NH3-TPD分析表明,具有中强酸与强酸相结合分布特点的催化剂适合于反应过程的协同催化作用要求。适宜的反应条件为:以SAPO-34分子筛作催化剂,反应温度400℃,甲醇混炼比15%,反应时间30 min。该条件能同时较好满足MTO和FCC汽油改质要求,产物汽油中烯烃含量较FCC汽油中的含量下降50%,并可获得较高的小分子烯烃产率,实现MTO转化。

以模型化合物研究MTG重汽油轻质化的热力学分析

MTG重汽油的轻质化对于提高MTG工艺的经济效益具有重要意义。本文以苯和均四甲苯的混合物为模型化合物研究了MTG重汽油中均四甲苯转化为C10以下芳烃化合物的轻质化过程，利用热力学原理计算了摩尔反应焓变、摩尔吉布斯自由能变和平衡常数。计算结果表明，在温度600～800K，各反应可以自发进行，但平衡常数小。温度和压力的改变反应系统平衡组成的影响不能显著，说明反应系统不是受热力学控制的。因此，系统很大程度受到动力学因素的影响，反应速率直接影响原料转化率和产物组成，在实际反应过程中，反应条件和催化剂的选择显得尤为重要。