噻吩、苯和正辛烷在NaY和CeY分子筛上的热脱附

采用智能质量分析仪(IGA),利用程序升温脱附法(TPD)研究了噻吩、苯和正辛烷在NaY和CeY分子筛上的热脱附行为,测定了升温速率为15 K/min时3种吸附质在NaY和CeY上的热重(TG)和微分热重(DTG)曲线。结果表明,3种吸附质在NaY上脱附比较容易,苯和正辛烷在CeY上脱附也很容易,但噻吩在CeY上脱附比较困难,噻吩有一部分不能完全脱附。CeY对噻吩具有较好的吸附选择性,而NaY的吸附选择性不好。     

频率响应法研究噻吩在分子筛上的吸附行为

运用频率响应方法（Frequency Response）研究了噻吩在NaY分子筛和CeY分子筛上的吸附行为,在（335～473） K和（13.3～133.3） Pa绘制频率响应谱图,并根据频率响应谱图计算每个吸附过程的动力学参数。研究结果表明,噻吩在NaY和CeY分子筛上的吸附均以吸附为速率控制步骤,噻吩在NaY分子筛上的吸附是由于π电子作用和孔填充机理;噻吩在CeY分子筛上的吸附过程是由于π络合和形成S—M键的机理。     

噻吩在CeY分子筛上的吸附行为

采用智能质量分析(IGA)和程序升温脱附和微分程序升温脱附（TPD/DTPD）法研究了噻吩在CeY上的热脱附行为和吸附热力学,并和NaY进行对比。发现噻吩在CeY分子筛上有很好的选择性吸附,噻吩和CeY分子筛之间的吸附主要是金属离子和硫原子的化学键力作用,而在NaY上的吸附作用属于分子间力作用。吸附热力学也证明了噻吩在CeY上既有物理吸附作用也有强的化学吸附作用。     

噻吩类硫化物在FAU分子筛上吸附的分子模拟研究

为了从分子层面探索焦化粗苯中噻吩类硫化物在催化剂上的吸附行为,指导焦化粗苯加氢脱硫精制,采用巨正则蒙特卡洛(GCMC)方法,在适宜的分子模拟条件下,研究了温度在473.15～673.15K时,单组分噻吩类硫化物在FAU分子筛上的吸附,获得了吸附热、吸附等温线和吸附位等信息;在焦化粗苯催化加氢条件,即压力0.01～1.0MPa、温度573.15K下,考察了多组分硫化物的竞争吸附。结果表明:在473.15～673.15K下,各硫化物的吸附热大小顺序为:2,5-二甲基噻吩>噻吩>2-甲基噻吩;在同一温度、压力下,分子量越小,饱和吸附量越大,饱和吸附量与分子量大小有关;在焦化粗苯催化加氢条件下,在多组分噻吩类硫化物的竞争吸附过程中分子大小占主导地位。     

影响CeY分子筛吸附脱硫性能因素的研究

通过液相离子交换法对NaY分子筛进行改性制得CeY分子筛，采用静态法考察了改性CeY分子筛中铈离子的负载量、焙烧温度、铈的价态、吸附水和分子筛骨架的结构对CeY分子筛吸附脱硫性能的影响。采用XRD和ICP分别对不同CeY分子筛的骨架结构及阳离子负载量进行了分析。结果表明，二次交换后,离子交换度达到88.9%，分子筛已达到交换平衡；最佳焙烧温度为500 ℃，温度过高会破坏分子筛的骨架结构；Ce(Ⅳ)Y的脱硫性能明显好于Ce(Ⅲ)Y；分子筛上的吸附水对硫化物的吸附能力也有较大的影响。     

Ce-CeY吸附剂的制备及其吸附脱除焦化粗苯中噻吩的研究

对CeY分子筛用等体积浸渍法制备了不同Ce浸渍量的吸附剂Ce-CeY。用XRD、氮吸附实验和FT-IR技术对不同吸附剂晶体结构及噻吩吸附行为进行了研究。结果表明,CeY分子筛中,Ce(Ⅳ)提供了丰富的吸附活性位,可以和噻吩形成π络合、S-Ce键配合及氢键作用;浸渍的Ce生成CeO2,分散在分子筛孔道内壁,使Ce-CeY孔径缩小,对噻吩具有分子尺寸选择作用。随着Ce浸渍量的增加,吸附剂的孔径逐渐缩小,吸附剂选择吸附噻吩性能先增大后减小。当温度为30℃、8.5%Ce-CeY(g)/模拟液(mL)为1/14、吸附时间为120min时,噻吩脱除率接近100%。     

改性NaY分子筛吸附脱硫性能的研究

以NaY分子筛为载体,采用液相离子交换法制备了一系列用于燃料油脱硫的负载金属离子的改性分子筛吸附剂.结果表明,AgY具有最高的硫容,其次是CuY、NiY、CeY、ZnY,硫化物吸附量顺序为:噻吩＞苯并噻吩＞二苯并噻吩.通过正交实验优化了Y分子筛的制备工艺,并对实验数据进行了方差分析,得到了最佳制备工艺条件:活性组分为A...     

离子改性Y分子筛吸附分离1,1,1,2-四氟乙烷/1,1-二氟-2-氯乙烯

用CaCl₂、La（NO₃）₃和Ce（NO₃） ₃溶液对NaY分子筛进行离子改性制备出CaY、LaY和CeY分子筛。将其及NaY为吸附剂,利用动态吸附法评价其吸附分离1,1,1,2-四氟乙烷（HFC-134a）产品中微量1,1-二氟-2-氯乙烯（HCFC-1122）的性能。同时采用X射线衍射（XRD）、吡啶红外（FTIR）和氨-程序升温脱附（NH₃-TPD）等手段对新鲜及再生后的吸附剂进行结构和表面性质表征。结果表明：CaY、LaY与CeY分子筛上的Brønsted酸中心可与HCFC-1122形成p-吸附配合物,从而将吸附流出气中HCFC-1122的残余率降低至1.0%以下;Brønsted酸强度越高,p-吸附配合物越容易形成,最低吸附温度越低（CeY     

噻吩在Cu+-13X上吸附平衡和动态数据测定

对噻吩在Cu -13X分子筛上的吸附平衡和动态数据进行了测定。对噻吩的吸附平衡数据用Langmuir模型进行拟合,得到了303、323 K下噻吩在Cu -13X上的饱和吸附量分别为232.86、74.78 mg/g;采用固定床测定了不同停留时间及不同初始浓度下的动态透过曲线,结果表明,在透过点以前动态吸附可以实现噻吩的零含量,缩短停留时间和增加初始浓度会影响吸附的透过曲线,实验结果为吸附工艺设计提供了一定的基础数据。     

频率响应法研究苯在NiY分子筛上的吸附行为

通过对分子筛的改性,构造各种类型、各种强度的能垒。测定在不同温度和不同压力下,吸附质在分子筛上的吸附扩散性能。采用频率响应(FR)技术研究苯在NiY分子筛上的吸附机理。分别选取的温度点为302K,373K和压力点为53.3~133Pa范围内测定FR谱图。研究结果表明,苯在NiY分子筛上是以吸附为速率控制步骤的传质过程,同时存在高频吸附和低频吸附两个不同的吸附过程。高频吸附是通过络合作用、低频吸附是以氢键作用为主的吸附过程。     

Adsorptive Removal of Thiophene from Benzene by NaY Zeolite Ion-Exchanged with Ce(IV)

The commercial NaY zeolite with the Si/Al ratio of 5:1 was selected and modified for researching the adsorptive removal of thiophene from benzene. The zeolite was ion-exchanged in Ce(NO₃)₃ solution and then calcined in muffle to prepare the CeY sorbent. The results show that it is a suitable method to prepare the sorbent removing thiophene from benzene that NaY zeolite is ion-exchanged by cerium in Ce(NO₃)₃ solution. The desulfurization efficiency of CeY sorbent increases obviously comparing with NaY zeolite. The effects of the calcination temperature, calcination time, concentration of Ce(NO₃)₃ solution, ion-exchange time, and ion-exchange times on the desulfurization capacity of CeY sorbent were also studied. The results show that the optimal CeY sorbent can be obtained when NaY zeolite is ion-exchanged in 0.5 mol/L Ce(NO₃)₃ solution at 100°C for 4 h, calcined at 700°C for 2 h, and repeated the above steps two times. The results of XRD and BET characterization indicate that those preparation conditions mainly influence on the crystallinity, specific surface area of CeY sorbent. The best CeY sorbent can remove thiophene to 136.8 mg/L from 550.0 mg/L in thiophene-benzene solution at ambient temperature and pressure with the agent-liquid ratio of 1:16 (g/mL).     

Y型沸石吸附噻吩的能量及结构异质性的分子模拟

采用GCMC方法计算了噻吩在全硅Y和NaY沸石上的吸附,通过变化不同的噻吩吸附量得到吸附能量的异质性,并基于主客体径向分布函数剖析了吸附能量的异质性。根据对噻吩分子与沸石之间能量的分析,噻吩分子与沸石之间的作用主要由短程的色散作用控制。NaY沸石上吸附表现出与全硅Y沸石明显不同的吸附位特征,钠离子的引入明显地增强了对噻吩的吸附作用。钠离子与噻吩之间的静电和色散作用是引起这两种不同化学组成沸石吸附热不同的重要因素。进一步对径向分布函数分析确定了NaY沸石中S—Na,CHsp2—Na之间存在独特的作用位。     

Thiophene conversion under mild conditions over a ZSM-5 catalyst

Refiners are nowadays actively considering the post-treating FCC gasoline processes as a viable and less costly approach for meeting sulfur environmental regulations. Most promising catalytic desulfurization processes do not require hydrogen addition, including between others the use of zeolites as adsorbents/catalysts. This type of desulfurization leads to the formation of significant amounts of coke, requiring keeping high catalyst activity a continuous twin fluidized bed system (fluidized-bed reactor, fluidized bed regenerator). This study evaluates the catalytic conversion of thiophene and/or thiophene in n-octane mixtures. Catalytic experiments are carried out in the CREC riser simulator under mild conditions, using H-ZSM5 zeolite dispersed in a silica matrix. The experimental results obtained demonstrate a higher selective conversion of thiophene over n-octane. It is shown that thiophene conversion proceeds via ring opening and alkylation yielding H₂S, alkyl-thiophenes, benzothiophene, and coke, with no measurable thiophene saturation or dimerization reactions observed. The experimental results are also supported with an extensive thermodynamic analysis that includes all the possible thiophene conversion pathways over zeolites. On this basis and using as a reference the observable measurable species, a reaction network is proposed to represent the thiophene catalytic conversion under the suggested gasoline post treatment conditions.     

改性介质的调变对NaY沸石后处理及其催化裂化性能的影响

Y型沸石作为FCC催化剂的主要活性组分,其酸性能和孔结构的改性效果直接决定了催化剂的性能优劣。选取酸性能为调变对象,分别采用两种不同的改性介质（CeY焙烧气氛和铵离子交换pH）对NaY沸石进行后改性处理。将所得的改性Y沸石进行了红外（IR）、X光电子能谱（XPS）和低温氮气物理吸附等表征分析。最后,使用真实油品VGO在固定流化床反应评价装置ACE上对改性样品的催化性能进行了评价。研究发现,选取Ce离子作为改性介质时,可通过改变后处理过程中的焙烧气氛来调变沸石不同酸类型的分布（Brønsted/Lewis acid,B/L）,实现对应的USY沸石的催化性能的调控;选取铵离子作为改性介质时,适当地调节第1次铵离子交换pH的苛刻程度,能够在调变超稳Y沸石B酸量的同时提高Y型沸石的介孔体积。     

Hydrothermal conversion of rice husk ash to faujasite-types and NaA-type of zeolites

The faujasite-type of zeolites (NaX and NaY) and NaA-type of zeolite were synthesized from rice husk ash (RHA) via the hydrothermal conditions. The combustion of rice husk at controlled temperature of 600 °C for an hour in open air produce more than 90% of amorphous silica in the ash which was reactive towards the synthesis of zeolites. The formation of zeolite NaY from RHA is metastable and thus, the seeding and ageing effects in the synthesis of zeolite NaY were investigated to avoid the formation of zeolite A or P as the impurities in zeolite NaY. Zeolites NaX and NaA were also successfully synthesized with high purity, absence of impurities and other phases, and high reproducibility. Thus, the amorphous forms of silica in RHA can be used as a source of silica for the synthesis of faujasite-types and NaA-type of zeolites.