Synthesis of ZSM-22/SAPO-11 composite molecular sieve-based catalysts with small crystallites and superior n-alkane hydroisomerization performance

To improve oil quality,ZSM-22/SAPO-11 composite molecular sieves were synthesized by adding ZSM-22 into a synthetic gel of SAPO-11 for n-decane hydroisomerization.The mass ratios of ZSM-22/(ZSM-22+SAPO-11)in the composite molecular sieves were optimized and the optimal ZSM-22/SAPO-11 composite(ZS-9)was obtained.The electrostatic repulsions between the ZSM-22 precursors and the SAPO-11 crystalline nuclei produced small ZSM-22 and SAPO-11 crystallites in ZS-9,which increased the specific surface area and mesopore volume and thereby exposed more acid sites.In comparison with conventional SAPO-11,ZSM-22 and their mechanical mixture,ZS-9 with smaller crystallites and the optimal medium and strong Brønsted acid centers(MSBAC)content displayed a higher yield of branched C_(10) isomers(81.6%),lower cracking selectivity(11.9%)and excellent stability.The correlation between the i-C_(10) selectivity and the MSBAC density of molecular sieves indicated that the selectivity for branched C_(10) isomers first increased and then decreased with increasing MSBAC density on the molecular sieves,and the maximum selectivity(87.7%)occurred with a density of 9.6×10^(−2)μmol m^(−2).

Investigation of ZSM-5/MCM-41 Composite Molecular Sieve for Reducing Olefin Content of FCC Gasoline

ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve were characterized by X-ray powder diffractometry,N2 adsorption isotherms,temperature programmed desorption of ammonia and scanning electron microscopy and their properties were analyzed.Using FCC gasoline as the feed,activities of different molecular sieves for reducing olefin content were investigated in a continuous high-pressure micro-reactor unit under the following conditions:a reaction temperature of 400℃,a reaction time of 2 h,a weight hourly space velocity of 3h-1,and a reaction pressure of 2.0 MPa.The results showed that the HMCM-41 molecular sieve had low reaction performance,and the HZSM-5 molecular sieve demonstrated high aromatization activity,while the ZSM-5/MCM- 41 composite molecular sieve exhibited a best olefin-reducing performance because of its high isomerization activity and moderate aromatization activity.With a largest olefin-reducmg capability and a reasonable distribution of products,the composite molecular sieve was more suitable for FCC gasoline upgrading compared to other three catalysts.

Preparation and characterization of A-type zeolite/SiO_2 molecular sieving membranes

To deal with the brittleness and crystal grain interfacial defects of zeolite membranes, and to confine the pore size distribution of inorganic membranes in a limited range, a process method for composite membranes of A-type zeolite/SiO 2 was discribed. A silica sol was mixed with nanocrystals of zeolite 4A in a suitable proportion, then the supported membranes was prepared by dip-coating method. The composite membranes prepared in first step was treated hydrothermally again, so nanocrystal zeolite 4A formed and located in the mesopores of the membranes, and the microstructure and pore size distribution of the membrane were modified greatly. The thermal stability, mineral phase, microstructure, and pore size distribution were examined via DTA-TG, X-ray diffractometer, scanning electron microscope (SEM), and BET equipment. The structure of the composite membranes remains high stability below 800 ℃. Its average pore size in a very limited range is smaller than that in the untreated membranes in hydrothermal condition, and the peak bands of the membrane pores are 4×10 -10 m, 1.8×10 -9 m, respectively.

ZSM-5基复合分子筛催化裂解制低碳烯烃研究进展

系统介绍了ZSM-5基复合分子筛的合成方法;针对典型的核-壳结构和微-介孔结构,阐述了复合结构对其孔隙结构、酸性质和水热稳定性等的调控方法和规律。在此基础上,详细综述了复合分子筛在甲醇、轻烃、生物质及其混合原料催化裂解制低碳烯烃领域的应用,提出复合分子筛催化材料未来发展前景。

加氢裂化复合分子筛催化剂研究进展

分子筛催化剂是加氢裂化的核心,传统分子筛催化剂只具有单一性质,无法兼具酸性强、水热稳定性及催化活性高等优点,因此复合分子筛催化剂的使用受到业界广泛关注。分别对微孔、介孔组成的复合分子筛进行介绍,通过将多种具有不同孔道结构和特性的分子筛进行复合,制备出在加氢裂化反应中性能优异的复合分子筛催化剂,并对加氢裂化催化剂的发展趋势进行展望。

Ni-MgO复合改性对HZSM-5分子筛催化性能的影响

采用等体积浸渍法制备了Ni和MgO改性的HZSM-5催化剂,考察Ni和MgO含量对甲醇制备丙烯的影响,并利用XRD、SEM、BET、NH 3-TPD等方法考察了Ni和MgO对HZSM-5分子筛的酸强度和结构的影响,结果表明,少量的Ni-Mg复合改性的HZSM-5分子筛MFI结构没有改变,但有效改变了催化剂的酸强度和孔径结构,显著降低催化剂中强酸含量,微孔孔径由0.5105 nm降为0.5016 nm,0.5%Ni-0.5%Mg/HZSM-5分子筛表现出较佳的丙烯选择性,丙烯的选择性提高了11.5%。

NaY分子筛复合材料及其催化裂化催化剂性能

以高岭土和水玻璃为原料,采用水热法原位晶化合成了NaY分子筛复合材料,通过离子交换法改性并制备出催化裂化催化剂,利用X射线荧光仪、N2吸附-脱附仪、扫描电子显微镜等仪器对试样进行结构表征,在固定流化床微型反应器装置上进行催化剂裂化反应性能评价。结果表明:该NaY分子筛复合材料的外比表面积为93.70 m^(2)/g,介孔孔容为0.19 cm^(3)/g,颗粒直径约在300~500 nm;改性后复合材料的介孔主要分布在2~20 nm,且为双孔分布,分布峰分别为3.8,5.6 nm;与常规NaY型分子筛催化剂相比,采用该NaY型分子筛复合材料所制备的催化剂其反应转化率、液化气和总液体收率依次提高6.18,5.16,1.61个百分点,重油收率下降3.34个百分点,生焦因子下降0.80。

铈锰复合氧化物高效催化分解臭氧

将Ce掺入MnO_(2)八面体分子筛(OMS-2)中得到铈锰氧化物催化剂。通过XRD,SEM,H_(2)-TPR,XPS等方法表征了催化剂的物理化学性质,模拟了该催化剂在高湿度下对高浓度臭氧的去除效果。实验结果表明,在OMS-2中掺Ce可使OMS-2晶型发生改变。Mn/Ce原子比为4的CeMn4的比表面积最大、粒径较小、氧空位浓度最高,因此具有优异的氧化还原性能,在湿度90%、体积空速700000 h^(-1)、反应时间420 min的条件下能实现臭氧分解率稳定在95%以上,且抗水性能强。铈锰复合氧化物有望成为工业上使用的催化分解臭氧的理想材料。

Cerium modified Y/SBA-15 composite molecular sieve catalyzed synthesis of n-butyl acetate

A novel Ce-Y/SBA-15 catalyst was prepared by modifying HY/SBA-15 microporous-mesoporous composite molecular sieve with cerium using the impregnation method. The characterization results from scanning electron microscopy/energy dispersive X-ray dispersive spectroscopy（SEM/EDS）, transmission electron microscopy（TEM）, and X-ray fluorescence（XRF） studies indicated that the Ce-modified catalyst maintained the microporous-mesoporous structure of Y/SBA-15. The Ce ions were found to be uniformly dispersed in the pores of the molecular sieve without aggregation. The results from pyrolysis coupled-Fourier transform infrared spectroscopy（Pyridine-FTIR） and temperature programmed desorption of ammonia（NH3-TPD） showed that the loading of cerium caused the hydroxyl group in the catalyst to display stronger Bronsted acidity. The efficiency of the modified Ce-Y/SBA-15 catalyst was evaluated by using it to catalyze the synthesis of n-butyl acetate. The optimal synthesis conditions were determined by orthogonal experiments. The highest esterification yield of 94.4% was obtained when the reaction time was 2.0 h, with acid/alcohol molar ratio of 1：1.2, and catalyst loading of 10 wt.%. The results in this study demonstrated that the loading of cerium and the structure of Y/SBA-15 microporous-mesoporous composite molecular sieve helped in improving the catalytic activity of this acidic catalyst.

Synthesis of a new meso/microporous composite molecular sieve of MCM-41/mordenite

An MCM-41/mordenite composite with two- fold porous structure and stepwise-distributed acidity was prepared for the first time by using zeolite mordenite as the silica-alumina source. The composite molecular sieve has been investigated and compared with a mechanical mixture of mordenite and MCM-41 for their structure, acidity and catalytic activity by means of XRD, N2 adsorption and desorption, HRTEM, DTG, NH3-TPD and catalytic reaction. The characterization results show that the structure and property of the composite molecular sieve are quite different from those of the mechanical mixture, which might be ascribed to the incorporation of secondary building units characteristic of zeolite mordenite into the mesoporous walls of the composite which gives rise to the thicker mesoporous walls, the higher hydrothermal stability and more strong acid sites. Furthermore, the new strategy could be used as a new general method for the preparation of catalysts for the reaction system with multifold large molecules, and the results were well confirmed by the dealkylation of C10+ aromatic hydrocarbon.

4A分子筛吸脱水特性研究

这是一篇陶瓷复合材料领域的论文。为了解4A分子筛在吸水脱水过程中水含量分布特征,采用高温脱水与低温吸水计算方法,探讨了不同脱附温度与气氛下4A分子筛水含量分布,结果表明,脱附温度为200~230℃时,在非真空气氛脱附时,有效残留水含量为4%~5%,有效脱附水含量达到了24%~25%,吸水率为83%~87%;在真空气氛下脱附时,有效残留水含量为1%~2%,有效脱附水含量达到了27%~28%,吸水率为93%~97%。为了使有效残留水含量低于2%,较佳脱附再生条件为真空气氛、脱附温度不低于200℃。采用差热失重法可以估算分子筛在非真空气氛下的有效脱水含量与有效残余水含量。真空脱附后样品吸水速率大于非真空脱附的吸水速率。

ZSM-5/SBA-15复合分子筛材料的制备及其加氢异构性能

合成了ZSM-5/SBA-15复合分子筛材料,并对其晶型结构、孔道参数、酸性质等物理化学性质和加氢异构化性能进行了表征和评价。结果表明:所合成的复合分子筛具有ZSM-5和SBA-15分子筛骨架结构,适宜的酸性和独特的介-微复合孔道结构;将其作为载体负载金属Pt后制得的Pt-ZSM-5/SBA-15催化剂,在正辛烷的加氢异构反应中,较纯硅SBA-15基催化剂Pt-SBA-15、微孔ZSM-5分子筛基催化剂Pt-ZSM-5和ZSM-5与SBA-15物理混合基催化剂Pt-ZS-H,具有更高的双支链异构产物选择性和较低的裂化选择性。

高岭土/醋酸钠插层复合材料合成NaY分子筛及其对Cr^(3+)离子的吸附性能

以直接插层法制备的高岭土/醋酸钠插层复合材料(KNM)为原料,采用原位晶化技术成功合成出NaY分子筛,研究了KNM的插层率及KNM添加量对NaY分子筛相对结晶度的影响及其在对重金属Cr^(3+)离子吸附方面的应用。通过粉末X射线衍射(XRD)、红外光谱(FT-IR)、N_(2)静态吸附法和电子扫描电镜(SEM)等手段对样品进行表征。结果表明:添加KNM能够合成出纯的NaY分子筛(N-NaY);当KNM添加质量分数低于10%时,与未添加KNM合成的NaY分子筛(R-NaY)相比,其相对结晶度均有所提高;随着KNM添加量的增加,N-NaY的相对结晶度先增加后降低;当加入质量分数1%的插层率90%的KNM时,N-NaY的相对结晶度达到最大值47%;相比于R-NaY,其具有较好的孔结构,孔体积为0.35 cm^(3)/g,BET比表面积为486.86 m^(2)/g;在最佳吸附温度20℃、吸附时间30 min、NaY分子筛用量1.0 g时,N-NaY对Cr^(3+)离子的吸附率可以达到95%。

空壳型SAPO-34分子筛催化剂的制备及催化MTO反应

采用复合模板剂合成出具有空壳结构的SAPO-34分子筛。使用XRD、SEM、BET对合成的分子筛样品进行表征,结果表明,所合成的分子筛为空壳型纯相SAPO-34分子筛,比表面积达到638.59 m^(2)/g。在催化甲醇制烯烃反应中,甲醇转化率达到100%,乙烯和丙烯(双烯)选择性达到85.3%。催化剂单程寿命为28 min,是常规SAPO-34分子筛的1.75倍。空壳型SAPO-34分子筛具有优异的MTO催化性能,主要原因是缩短了反应产物从分子筛孔道扩散出来的路径,减少了产物二次反应的发生。

干旱胁迫下新型复合水凝胶对烟草生理特性的影响

【目的】探究新型复合水凝胶对干旱胁迫下烟苗生理特性的影响。【方法】通过盆栽试验,设计了水凝胶添加量和水凝胶种类2个试验因素,其中水凝胶添加量分别为土壤干质量的0.1%、0.5%、0.9%,水凝胶分别为商用水凝胶HS、新型复合水凝胶HM(聚乙烯醇-丙烯酸-分子筛水凝胶)和HB(聚乙烯醇-丙烯酸-生物炭水凝胶),以不添加水凝胶为对照(CK),研究新型复合水凝胶对干旱胁迫下烟草生物量积累、根系发育、光合系统及氧化应激的影响。【结果】在同一水凝胶添加量下,与HS处理相比,HM、HB处理均有效提高干旱胁迫下烟草鲜质量、干质量及总含水率。与CK相比,HM、HB处理最大可使鲜质量分别提高153.91%、126.34%。且在同一水凝胶添加量下,与HS处理相比,HM、HB处理烟草的总根长、总根表面积、平均根径、根尖数和根体积显著增加,烟草的根系活力、烟草光合参数、SPAD值提高,叶片气孔状态改善;烟草SOD(超氧化物歧化酶)、POD(过氧化物酶)和CAT(过氧化氢酶)活性及可溶性蛋白量提高,MDA(丙二醛)量显著降低,烟草抗逆性增强。【结论】添加量为土壤干质量0.9%的HM、HB水凝胶可以有效减轻干旱胁迫对烟草的影响,提高烟草抗旱能力。

颗粒13X分子筛复合材料去除水中Cu^(2+)的机理及共存Pb^(2+)、Cd^(2+)、Zn^(2+)的影响研究

制备了颗粒13X分子筛复合材料,将其装填为固定床,探究复合材料去除水中Cu^(2+)的机理及共存重金属离子Pb^(2+)、Cd^(2+)和Zn^(2+)对复合材料固定床去除Cu^(2+)性能的影响。结果表明,在进水流速为150 mL·min^(-1)、Cu^(2+)浓度为100 mg·L^(-1)的条件下,固定床运行23.5 h后,Cu^(2+)达到穿透点,复合材料对Cu^(2+)的饱和富集量为1.58 mmol·g^(-1)(铜含量达10.03%)。颗粒13X分子筛复合材料去除Cu^(2+)的机理主要包括离子交换吸附和表面沉淀。Cu^(2+)-Pb^(2+)、Cu^(2+)-Cd^(2+)和Cu^(2+)-Zn^(2+)二元体系的运行结果表明,Pb^(2+)、Cd^(2+)和Zn^(2+)的共存分别使Cu^(2+)的穿透时间提前了34.0%、40.4%和53.6%,进出水中Cu^(2+)浓度相等时复合材料对Cu^(2+)的富集量分别降低到0.28 mmol·g^(-1)、1.08 mmol·g^(-1)和1.55 mmol·g^(-1),影响强弱顺序为Pb^(2+)>Cd^(2+)>Zn^(2+)。水合离子直径和水合能越小、电负性越大的共存重金属离子,对复合材料去除Cu^(2+)产生的不利影响越强。

SAPO-34分子筛催化剂制备及催化流化床甲醇制烯烃反应

采用复合模板剂合成出较小晶粒结合而成的SAPO-34分子筛。使用XRD、SEM、BET对合成的分子筛样品进行了表征,结果表明,所合成的分子筛为纯相SAPO-34分子筛,比表面积达到615.217 m^(2)/g。采用合成的SAPO-34分子筛为原粉,加入高岭土为基质、硅溶胶为黏结剂,喷雾干燥得到成型催化剂。在催化流化床甲醇制烯烃(MTO)甲醇反应中,甲醇质量空速为6.0 h^(-1)条件下,甲醇转化率为99.35%,催化剂活性时间为65 min,乙烯和丙烯(双烯)选择性达到90.37%,焦炭选择性为3.89%。在相同条件下,常规SAPO-34分子筛催化剂活性时间为40 min,使用二异丁胺制备的SAPO-34分子筛催化剂活性时间是常规SAPO-34分子筛催化剂的1.625倍。使用二异丁胺合成的SAPO-34分子筛MTO催化剂具有优异的流化床甲醇制烯烃性能,主要原因是小晶粒团聚而成的SAPO-34分子筛粒,反应产物从分子筛孔道扩散出来的路径变短,减少了产物二次反应的发生。

分子筛复合凝胶对植烟土壤理化特性及烤烟产量和品质的影响

【目的】研究自制分子筛复合凝胶对烟草根际土壤理化特性及烤后烟叶产量和品质的影响,探究提高峡江烟区烟叶品质的土壤改良措施。【方法】以云烟87为材料,设置22.5 kg/hm^(2)自制空白凝胶、45 kg/hm^(2)商用农林抗旱保水剂1、45 kg/hm^(2)商用农林保水剂2、22.5 kg/hm^(2)分子筛和45 kg/hm^(2)自制分子筛复合凝胶5个处理,以不施用保水剂为对照,研究施加商用保水剂、自制分子筛复合凝胶对烟草根际土壤理化特性及烤后烟产质量的影响。【结果】施加自制分子筛复合凝胶后,在取样期内土壤含水率、碱解氮、速效钾、速效磷含量较对照均显著提高(P<0.05),增幅分别为16.26%~41.22%,14.16%~26.55%,13.04%~27.03%和16.97%~30.23%;土壤蔗糖酶、脲酶活性均最高,且与对照差异达到显著水平。烤后烟叶厚度、叶质重、拉力、平衡含水率、填充值、单叶质量较对照分别显著提高12.50%,6.07%,24.51%,10.75%,30.38%和40.41%,而含梗率降低2.46%;烤烟总氮、钾、氮碱比、钾氯比较对照分别显著提高26.53%,17.62%,14.86%和59.45%,氯含量显著降低25.68%;苯丙氨酸类降解产物、新植二烯、中性致香物质总量较对照分别提高35.51%,36.21%和31.97%,烤烟化学成分更为适宜协调,感官质量评价总分最高。产量、产值、上等烟比例、均价较对照分别增加8.73%,14.08%,31.03%和5.19%。【结论】施加自制分子筛复合凝胶可有效改良植烟土壤,改善烟叶品质,提高烟叶产量。

微孔-介孔复合分子筛的合成研究进展

系统综述了近几年微孔-介孔复合分子筛的合成研究工作,将微孔-介孔复合分子筛的复合模式分为两大类:微孔分子筛和介孔分子筛两种材料的复合以及介孔孔道与微孔孔道在一种分子筛材料中的复合,分别介绍了不同复合模式的微孔-介孔复合分子筛的合成方法,包括离子交换法、静电匹配法、微孔沸石硅源法、特殊模板法、纳米组装法、孔壁晶化法等。