C5烷烃分子在AlPO4-5分子筛中吸附的分子模拟研究

采用分子水平计算机模拟方法研究了环戊烷、正戊烷和2－甲基丁烷在AlPO4-5分子筛中的吸附，得到了有关吸附平衡常数、吸附热、吸附等温线以及平均势能等。结果表明，在373 K，2－甲基丁烷的饱和吸附量高于其他两种异构体；473 K，环戊烷的饱和吸附量高于其他两种异构体；573 K，在所测试的压力范围内，环戊烷的吸附量都高于其他两种异构体，2－甲基丁烷的吸附量高于正戊烷。C5烷烃分子在AlPO4-5中吸附量的不同是由于他们在分子筛中的排列方式不同而引起的。低吸附量时C5烷烃分子平均势能不随吸附量变化；高吸附量时平均势能随着吸附量的增加而降低；而2－甲基丁烷和环戊烷分子的平均势能变化更加明显。     

面向C4烯烃混合物吸附分离的真实金属-有机骨架材料高通量筛选

常规的烯烃/烷烃冷冻加压精馏分离过程具有高能耗和低效率的特点, 吸附分离技术可以在温和条件下高效纯化烯烃分子而在烯烃/烷烃分离领域展现出广阔应用前景. 本工作采用高通量筛选技术从12723个真实金属-有机骨架(MOF)材料中筛选具有优异C4烯烃混合物选择性吸附性能的吸附剂, 用于1,3-丁二烯的分离纯化. 首先, 根据MOF材料的结构参数进行筛选获得了7681个具有合适孔径和比表面积的吸附剂. 然后, 采用分子力学方法计算出上述吸附剂的力学性能, 以UIO-66力学性能为阈值得到959个结构稳定的候选MOF材料. 接下来采用巨正则蒙特卡洛(GCMC)方法模拟出298 K、0.1 MPa下五元等摩尔C4烯烃混合物在不同候选MOFs中的选择性吸附行为, 根据候选MOFs对1,3-丁二烯的吸附性能分值(APS)进行排序, 得到具有最佳吸附分离性能的8种MOF材料. 通过定量构效关系、吸附等温线及理想吸附溶液理论等揭示了高吸附分离性能MOFs的结构特征, 利用穿透曲线模拟进一步验证了填充最优吸附剂RIGPEE01的固定床能够有效分离2-顺式丁烯/1,3-丁二烯双组分混合物. 最后, 通过径向分布函数和结合能计算分析, 确定RIGPEE01对1,3-丁二烯产生优先吸附的机理主要归因于Cu(I)强吸附位点、π键耦合效应和尺寸筛分效应. 本工作提出的高通量筛选方法以及从分子尺度理解MOF材料应用于烯烃分离机制的视角, 为进一步开发烯烃/烷烃混合物分离的新型吸附剂奠定了理论基础.     

分子动力学模拟1-丁烯和正丁烷在MCM-22分子筛中的扩散行为

应用分子动力学方法研究了1-丁烯和正丁烷在MCM-22型分子筛(ITQ-1)中的扩散行为. 得到了两种物质在ITQ-1分子筛两个独立孔道中的均方位移曲线、自扩散系数和扩散轨迹. 计算结果表明, 在温度为400 K时, 1-丁烯或正丁烷在十元环孔道中的扩散明显低于在超笼中的扩散, 吸附质在超笼的底部和顶部的扩散明显低于在超笼中心的扩散; 1-丁烯和正丁烷在ITQ-1分子筛的超笼中两者扩散速率较为相似, 而在十元环中, 两者的扩散速率差别较大.可以推测, 选择性催化主要发生在十元环中.     

在 La-Cr-Fe 钙钛矿型催化剂上丁烷、反-2-丁烯及顺-2-丁烯深度氧化动力学

在La-Cr-Fe 钙钛矿型催化剂上用玻璃外循环无梯度反应器研究了丁烷、反-2-丁烯及顺-2-丁烯深度氧化动力学。丁烷、反-2-丁烯及顺-2-丁烯深度氧化动力学服从L-H机理模型。用正交设计法估计了动力学方程中的参数值。丁烷、反-2-丁烯及顺-2-丁烯深度氧化的L-H 机理模型为脉冲实验鉴别。用脉冲色谱法测定了“2-丁烯”及O_2的吸附热。丁烷、反-2-丁烯及顺-2-丁烯深度氧化的CO_2生成速度用(7)式描述。     

噻吩在γ-Mo_2N(100)表面上加氢脱硫反应的密度泛函理论研究

利用密度泛函理论研究了γ-Mo2N(100)表面上的噻吩加氢脱硫(HDS)过程.噻吩在γ-Mo2N(100)表面上不同作用形式的结构优化结果显示,η5-Mo2N吸附构型最稳定,具有最大的吸附能(-0.56 eV),此时噻吩通过S原子与Mo2原子相连平行表面吸附在四重空位(hcp位).H原子和噻吩在hcp位发生稳定共吸附,hcp位是噻吩HDS的活性位点.噻吩在γ-Mo2N(100)表面进行直接脱硫反应,HDS过程分为S原子脱除和C4产物加氢饱和两部分.过渡态搜索确定了HDS最可能的反应机理及中间产物,首个H原子的反应需要最大的活化能(1.69 eV),是噻吩加氢脱硫的控速步骤.伴随H原子的不断加入,噻吩在γ-Mo2N(100)表面上优先生成―SH和丁二烯,随后―SH加氢生成H2S,丁二烯加氢饱和生成2-丁烯和丁烷.由于较弱的吸附,H2S、2-丁烯和丁烷很容易在γ-Mo2N(100)表面脱附成为产物.     

正丁烷在金属钼酸盐催化剂上的氧化脱氢

 用柠檬酸盐法合成了第一系列过渡金属(Cr,Mn,Fe,Co,Ni,Cu和Zn)及Mg的钼酸盐催化剂,研究 了它们对正丁烷氧化脱氢反应的催化作用. 结果表明,这些钼酸盐催化剂的催化性能受阳离子的影响较大. CoMoO4催化剂具有最高的催化活性和较高的选择性,其催化性能与文献报道的对正丁烷氧化脱氢反应催化性能最好的ZrP2O7和Mg3V2O8催化剂大致相当; MgMoO4催化剂虽然选择性较高,但活性较低; Cr2(MoO4)3上基本没有C4烯烃生成; 其它钼酸盐催化剂对正丁烷氧化脱氢反应的催化活性和对烯烃的选择性都较低. XRD,NH3-TPD和H2-TPR的研究结果表明,催化剂为单一的钼酸盐晶相,催化剂的性能由其氧化还原性决定而与其表面酸量没有直接关系. 通过对产物分布的分析,提出了正丁烷在CoMoO4催化剂上的氧化脱氢反应途径. 在558 ℃,正丁烷发生氧化脱氢生成正丁烯和丁二烯以及氧化燃烧生成CO2三个平行竞争反应的竞争分率分别约为75%,10%和15%. 在正丁烷转化率较高的条件下,产物中的CO2主要来自C4烯烃的再氧化反应,而CO则完全来自C4烯烃的再氧化.     

通过FeOx修饰Pd/Al2O3催化剂提高催化1,3-丁二烯加氢活性和选择性

石油脑裂解制备的烯烃流中通常含有 ～1％ 二烯烃或者炔烃,其含量必须降低到10 ppm以下以避免其对下游聚合催化剂的毒化作用.对这些副产物选择性加氢生成单烯烃是降低其含量最有前景的方法.Pd基催化剂具有高的加氢活性和选择性,是目前最为常用的加氢催化剂,但是它也存在高转化率下选择性较低和容易因积碳而失活的问题.合成Pd基双金属催化剂和对Pd催化剂进行氧化物包裹是目前最为常用的方法,但是这两种方法往往在提高选择性的同时,降低了Pd催化剂的加氢活性.本文利用原子层沉积(ALD)FeOx修饰Pd/Al2O3催化剂,在提高Pd催化剂选择性的同时,1,3-丁二烯选择性加氢活性也得到提高.表征结果发现,该样品中Pd负载量为1％,Fe负载量则随着原子层沉积FeOx周期增加而逐渐增加;催化剂中Pd颗粒大小约为7 nm,其表面并未观察到FeOx覆盖层;Pd,Fe元素分布表明FeOx在Pd颗粒表面生长.CO红外漫反射光谱也发现,随着ALD FeOx周期的增加,CO在Pd颗粒表面的吸附特征峰强度逐渐降低,表明FeOx逐渐覆盖Pd颗粒表面;与此同时,随着FeOx包裹周期的增加,CO吸附在Pd(111)面的特征吸收峰相对于其吸附在边角位的特征峰,降低得更为明显.这表明FeOx优先覆盖Pd(111)面,而选择性地将Pd低配位点暴露,与ALD Al2O3包裹Pd颗粒的结果恰恰相反.X射线光电子能谱分析表明,在所有催化剂中Fe均以+3价形式存在;同时,因为Pd-FeOx间存在强相互作用,所以随着FeOx包裹周期的增加,金属态Pd逐渐向高结合能方向移动,使表面Pd处于缺电子状态.随后,我们对不同FeOx周期包裹Pd催化剂进行了1,3-丁二烯加氢活性测试.在25 oC时Pd/Al2O3催化1,3-丁二烯转化率为6.7％;随着温度升高,转化率逐渐上升,至43 oC时达100％.相反,在26 oC时,30Fe/Pd/Al2O3对1,3-丁二烯的转化率为45％,远高于Pd/Al2O3催化剂;这可能是因为缺电子的Pd或Pd-FeOx界面存在所致.Pd/Al2O3催化剂在较低的转化率(<75％)下,1-丁烯、反式-2-丁烯和顺式-2-丁烯选择性分别为74％,20％和6％;随着转化率的增加(75％～90％),1-丁烯选择性急剧下降,丁烷选择性快速上升,反/顺-2-丁烯选择性也略有增加,表明此时次级反应1-丁烯加氢占主导,同时伴随着1-丁烯异构化反应;当转化率继续增加(>90％),1-丁烯,反/顺-2-丁烯加氢生成丁烷为主要反应,此时丁烷选择性急剧上升,至转化率为99％时,丁烯选择性仅为52％.而当Pd催化剂表面存在FeOx时,丁烯选择性随着FeOx周期增加而逐渐增加,尤其是在较高转化率下(>75％);对于30Fe/Pd/Al2O3催化剂,转化率为99％时,丁烯选择性高达95％.这主要是因为在高转化率下,FeOx将Pd颗粒表面分割成较小的Pd团簇,降低了Pd颗粒表面吸附氢气浓度,抑制了丁烯加氢反应,而次级反应1-丁烯异构化占主导,使得丁烯选择性不变.     

烷烃在丝光沸石型分子筛中吸附和扩散行为

采用巨正则系综蒙特卡罗(grand canonical Monte Carlo, GCMC)与分子动力学(molecular dynamics, MD)相结合的方法, 研究烷烃分子在丝光沸石(MOR)型分子筛中的吸附和扩散性质. 采用GCMC 方法研究温度为300 K、330 K时, MOR型分子筛中甲烷、乙烷、丙烷、丁烷的吸附. 研究表明, 随着压力的增加吸附量增加, 随温度的升高吸附量有所降低. 饱和吸附量从大到小依次为: 甲烷>乙烷>丙烷>丁烷. 由模拟所得到的单组分吸附等温线, 通过理想吸附溶液理论(IAST)计算二元混合物的吸附平衡相图, 模拟结果与计算结果一致. 采用分子动力学方法, 研究乙烷、丙烷在MOR分子筛上的扩散性质, 结果表明各个方向上的扩散系数不同, z方向上的扩散系数最大.     

通过FeO_x修饰Pd/Al_2O_3催化剂提高催化1,3-丁二烯加氢活性和选择性（英文）

石油脑裂解制备的烯烃流中通常含有~1%二烯烃或者炔烃,其含量必须降低到10 ppm以下以避免其对下游聚合催化剂的毒化作用.对这些副产物选择性加氢生成单烯烃是降低其含量最有前景的方法.Pd基催化剂具有高的加氢活性和选择性,是目前最为常用的加氢催化剂,但是它也存在高转化率下选择性较低和容易因积碳而失活的问题.合成Pd基双金属催化剂和对Pd催化剂进行氧化物包裹是目前最为常用的方法,但是这两种方法往往在提高选择性的同时,降低了Pd催化剂的加氢活性.本文利用原子层沉积(ALD)FeO_x修饰Pd/Al_2O_3催化剂,在提高Pd催化剂选择性的同时,1,3-丁二烯选择性加氢活性也得到提高.表征结果发现,该样品中Pd负载量为1%,Fe负载量则随着原子层沉积FeO_x周期增加而逐渐增加;催化剂中Pd颗粒大小约为7 nm,其表面并未观察到FeO_x覆盖层;Pd,Fe元素分布表明FeO_x在Pd颗粒表面生长.CO红外漫反射光谱也发现,随着ALD FeO_x周期的增加,CO在Pd颗粒表面的吸附特征峰强度逐渐降低,表明FeO_x逐渐覆盖Pd颗粒表面;与此同时,随着FeO_x包裹周期的增加,CO吸附在Pd(111)面的特征吸收峰相对于其吸附在边角位的特征峰,降低得更为明显.这表明FeO_x优先覆盖Pd(111)面,而选择性地将Pd低配位点暴露,与ALD Al_2O_3包裹Pd颗粒的结果恰恰相反.X射线光电子能谱分析表明,在所有催化剂中Fe均以+3价形式存在;同时,因为Pd-FeO_x间存在强相互作用,所以随着FeO_x包裹周期的增加,金属态Pd逐渐向高结合能方向移动,使表面Pd处于缺电子状态.随后,我们对不同FeO_x周期包裹Pd催化剂进行了1,3-丁二烯加氢活性测试.在25 oC时Pd/Al_2O_3催化1,3-丁二烯转化率为6.7%;随着温度升高,转化率逐渐上升,至43 oC时达100%.相反,在26 oC时,30Fe/Pd/Al_2O_3对1,3-丁二烯的转化率为45%,远高于Pd/Al_2O_3催化剂;这可能是因为缺电子的Pd或Pd-FeO_x界面存在所致.Pd/Al_2O_3催化剂在较低的转化率(75%)下,1-丁烯、反式-2-丁烯和顺式-2-丁烯选择性分别为74%,20%和6%;随着转化率的增加(75%~90%),1-丁烯选择性急剧下降,丁烷选择性快速上升,反/顺-2-丁烯选择性也略有增加,表明此时次级反应1-丁烯加氢占主导,同时伴随着1-丁烯异构化反应;当转化率继续增加(90%),1-丁烯,反/顺-2-丁烯加氢生成丁烷为主要反应,此时丁烷选择性急剧上升,至转化率为99%时,丁烯选择性仅为52%.而当Pd催化剂表面存在FeO_x时,丁烯选择性随着FeO_x周期增加而逐渐增加,尤其是在较高转化率下(75%);对于30Fe/Pd/Al_2O_3催化剂,转化率为99%时,丁烯选择性高达95%.这主要是因为在高转化率下,FeO_x将Pd颗粒表面分割成较小的Pd团簇,降低了Pd颗粒表面吸附氢气浓度,抑制了丁烯加氢反应,而次级反应1-丁烯异构化占主导,使得丁烯选择性不变.     

11-丁烯在MCM-2222分子筛中的吸附与扩散: Monte Carlo与动力学模拟研究

采用巨正则Monte Carlo方法和分子动力学方法研究了11-丁烯在MCM-2222分子筛中的吸附现象和扩散行为, 得到了11-丁烯吸附在该分子筛孔道中的相互作用能和在不同孔道中的扩散轨迹和扩散系数. 结果表明11-丁烯在MCM-2222分子筛中主要存在两个相互作用能区间, 11-丁烯优先吸附在十元环孔道中; 11-丁烯的扩散和移动主要发生在十二元环超笼的中部, 十元环孔道中的11-丁烯扩散速度明显小于十二元环超笼系统中的扩散速度.     

Selective adsorption of 2,3-DCDD and 1,2,3,4-TCDD on *BEA,EMT, FAU and MFI-type zeolites as alternative adsorbents for on-line dioxin monitoring

The aim of this study is to evaluate the capabilities of zeolites as selective sorbents for on-line dioxin monitoring. The adsorption isotherms of 2,3-DCDD and 1,2,3,4-TCDD from isooctane on several zeolites with different pore sizes (*BEA, EMT, FAU and MFI-type zeolites) are determined. Selective adsorption is shown for FAU and EMT-type zeolites. 2,3-DCDD is adsorbed by FAU with the highest adsorption capacity and affinity while 1,2,3,4-TCDD is not adsorbed whatever the zeolites. The adsorption of 2,3-DCDD inside the pores of FAU is qualitatively confirmed by diffuse reflectance UV spectrometry and thermogravimetry measurements.     

硅沸石完美骨架上的吸附Ⅲ.氯氟烃在MFI和FAU上的吸附热

测定不同温度下三种氯氟烃F-11(CFCl3),F-12(CF2Cl2)和F-22(CHF2Cl)在疏水高硅MFI和FAU沸石上的吸附等温线,以研究其吸附热效应。根据Clapeyron-Clausius方程,由吸附等温线,计算不同覆盖度C的等量吸附热Qst(C)和平均吸附热Qst^*(△Ha)。上述吸附质在两种沸石上吸附热的大小顺序均为：△Ha(MFI)＞△Ha(FAU)。在同种沸石上,吸附热的大小顺序为：△Ha(F-11)＞△Ha(F-12)＞△Ha(F-22).298K时的吸附等温线和△Ha的变化趋势显示,对能允许氯氟烃分子自由进出其孔道的FAU沸石,吸附质分子越大,低分压吸附量(V)越大,吸附热(△Ha)也越大。而孔道对吸附质分子有空间限制作用的MFI沸石,其吸附热、分子尺寸与饱和吸附量(Vm)间关系比较复杂。选择去除氯氟烃的沸石吸附剂应综合考虑△Ha与饱和吸附容量Vm。     

硅沸石完美骨架上的吸附Ⅱ.乙胺、正戊烷、乙醇在 FAU型沸石上的吸附热

用测定吸附等温线法研究乙胺、正戊烷和乙醇在疏水高硅FAU沸石上的吸附热效应。根据Clapeyron-Clausius方程,处理吸附等温线,得到不同覆盖度C(C=被吸附分子数/晶胞)的等量吸附热Qst(C)(一定覆盖度C时由Clapeyron-Clausius方程计算的吸附热)及平均等量吸附热Qst^*(一定温度区间里等量吸附热Qst的平均值),以及Qst^*与沸点蒸发热△Hv的差值△H1(定义为相互作用强度△H1=Qst^*-△Hv)。所研究的三种有机分子的△H1的次序为△H1(乙胺)>△H1(正戊烷)>>△H1(乙醇)。这与AT值(定义为脱附温度Td与吸附质的沸点温度Tb的差值,无需单位)有正相关关系。由AT值观察到的高硅FAU沸石Si-O骨架与被吸附乙胺之间可能存在的强相互作用、为本研究测定的热力学定量数据△H1值所证明。     

Detailed process of adsorption of alkanes and alkenes on zeolites

The adsorption of alkanes and alkenes on zeolites is investigated by comparing the adsorption characteristics for three types of zeolite: ferrierite, ZSM-5, and mordenite. The activation energy for the diffusion of propane and n-butane on ferrierite and the heat of adsorption of C(2)-C(4) alkanes and alkenes on zeolites and silica are estimated based on Fourier transform infrared spectroscopy, and the diffusion processes in the micropores are elucidated by comparing the results with previously reported activation energies for n-butene diffusion. The adsorption of 1-butene on mordenite is also examined. The structure and process of experimentally observable adsorption is found to differ depending on the type of zeolite and adsorbing molecule, reflecting differences in the sizes of molecules and pores. This differing behavior is utilized to interpret the elementary adsorption processes of alkanes and alkenes on zeolites.     

Adsorption of Carbamazepine in All-Silica Zeolites Studied with Density Functional Theory Calculations**

The anticonvulsant drug carbamazepine (−) is an emerging contaminant of considerable concern due to its hazard potential and environmental persistence. Previous experimental studies proposed hydrophobic zeolites as promising adsorbents for the removal of carbamazepine from water, but only a few framework types were considered in those investigations. In the present work, electronic structure calculations based on dispersion-corrected density functional theory (DFT) were used to study the adsorption of CBZ in eleven all-silica zeolites having different pore sizes and connectivities of the pore system (AFI, ATS, BEA, CFI, DON, FAU, IFR, ISV, MOR, SFH, SSF framework types). It was found that some zeolites with one-dimensional channels formed by twelve-membered rings (IFR, AFI) exhibit the highest affinity towards CBZ. A “good fit” of CBZ into the zeolite pores that maximizes dispersion interactions was identified as the dominant factor determining the interaction strength. Further calculations addressed the role of temperature (for selected systems) and of guest-guest interactions between coadsorbed CBZ molecules. In addition to predicting zeolite frameworks of particular interest as materials for selective CBZ removal, the calculations presented here also contribute to the atomic-level understanding of the interaction of functional organic molecules with all-silica zeolites.     

Low-temperature adsorption/storage of hydrogen on FAU, MFI, and MOR zeolites with various Si/Al ratios: effect of electrostatic fields and pore structures

Several zeolites, such as faujasite, mordenite, and ZSM-5, with various aluminum contents have been used to analyze the effect of aluminum or cation concentration (strength of electrostatic field) on hydrogen adsorption at low temperature. Irrespective of the zeolite structure, the adsorption capacity, isosteric heat of adsorption (-DeltaHads), surface coverage, and micropore occupancy increase with increasing aluminum content of a zeolite. Zeolites with a higher amount of aluminum favorably adsorb hydrogen at relatively low pressures. For zeolites with similar aluminum contents, the adsorption capacity, isosteric heat of adsorption, surface coverage, and micropore occupancy are in the order of mordenite>ZSM-5>faujasite, probably due to differing pore sizes and the presence or absence of pore intersections. This work demonstrates that zeolites with strong electrostatic fields and narrow pores without intersections are beneficial for high hydrogen uptake.     

Neopentane and solid acids: direct hydron exchange before cracking

The hydrogen/deuterium exchange reaction of 2,2-dimethylpropane (neopentane) over D(2)O-exchanged zeolites (MOR, FAU, BEA, MFI) using a batch recirculation reactor was studied by means of gas chromatography coupled with mass spectrometer. In the temperature range 473-573 K, H/D exchange proceeds without side reaction such as cracking at short contact times. Indeed the C-H bond has appeared favorably involved in the activation of neopentane compared to the less accessible C-C bond. The transition state allowing hydron exchange is most likely a carbonium species (pentacoordinated carbon) as in the case of the H/D exchange between methane and solid acid. The activation energies of the H/D exchange between neopentane and zeolites are the same for all zeolites indicating a common carbonium ion type transition state. On the basis of previous results in the case of the exchange between methane and liquid superacids, the deuterium exchange rates in neopentane were tentatively related to the acidity of the solids. However the order of activity MOR > MFI > BEA > FAU seems to be related to the size of the pores, which may suggest the involvement of a confinement effect in the zeolites cavities. Moreover we found that H/D exchange takes also place between neopentane and deuterated sulfated zirconia (SZ) emphasizing its strong acidity.     

In situ infrared molecular detection using palladium-containing zeolite films

In situ IR detection of carbon monoxide in the presence of hydrocarbons (methanol and pentane) using Pd-containing zeolite thin films is reported. The thin films are prepared by spin coating deposition of nanosized LTL and BEA type zeolites suspensions; the palladium clusters are introduced in the nanosized zeolites by ion exchange followed by γ radiolysis of the coating suspensions. The Pd-containing zeolite films with a thickness of 200 nm are exposed to a single gas (either CO or hydrocarbons) or gas mixtures in the presence of water (100 ppm), and the IR spectra are collected continuously at 25, 75, and 100 °C. The fast recognition of very low concentrations of CO (2-100 ppm) in the presence of highly concentrated vapors of methanol or pentane (400-4000 ppm) with the Pd-containing zeolite films is demonstrated. The detection of CO and hydrocarbons is instant, which is a function of the low thickness of the films, small size of the individual zeolite crystals, and regular size and high stability of the Pd clusters in the zeolite films. The heat of adsorption for all experiments is similar (15 kJ.mol(-1)), which is explained with weak interactions between the carbon monoxide and palladium clusters in the zeolite films at temperatures below 100 °C. The nanosized zeolites with homogeneously distributed Pd clusters deposited in thin films demonstrate high molecular recognition capacity toward low concentrations of carbon monoxide under real environmental conditions, i.e., in the presence of water and hydrocarbons.     

Comparative study on the gas-phase adsorption of hexane over zeolites by calorimetry and inverse gas chromatography

The scope of this work is to carry out a systematic comparison of inverse gas chromatography (IGC) and microcalorimetry as tools for the study of the gas-phase adsorption of organic vapours (using hexane as model compound) on zeolitic materials (using different Mn, Co and Fe-exchanged NaX and CaA zeolites). Adsorption isotherms were recorded using both techniques in the temperature range of 150-250 degrees C, being observed that the shape of the isotherms obtained with the dynamic (IGC) and static (microcalorimetry) techniques was surprisingly similar in the pressure range at which both techniques are applicable (low surface coverages). Concerning to the measurement of the strength of the adsorption, calorimetric data provide two parameters related to the adsorption enthalpy: the initial differential heat and the isosteric adsorption enthalpy. A great coincidence was found between the last one and the adsorption enthalpy determined by IGC (4-20% of difference, depending on the studied material). The behaviour of the initial differential heat depends strongly on the studied material, being in some cases closely related to the other two parameters and temperature-independent (in the case on Mn-exchanged zeolites), whereas for the Co-CaA and Fe-CaA zeolites, it is temperature-dependent, being not correlated with the other parameters in this case. The main conclusion of this work is that IGC is an attractive alternative to the static microcalorimetric data for obtaining information on the adsorption of organic compounds on microporous materials.     

Aluminosilicates with different pores structure in the synthesis of 2,2,4-trimethyl-1,2-dihydroquinoline and <Emphasis Type="Italic">N</Emphasis>-phenyl-2-propanimine

Physicochemical characteristics of microporous zeolites of various structural type (FAU, BEA, MTW), micro-meso-macroporous zeolite (H-Ymmm), and mesoporous aluminosilicate (ASM) were studied. Their catalytic activity in the reaction of aniline with acetone was examined. It was found that 2,2,4-trimethyl-1,2-dihydroquinoline was the main reaction product on the catalysts H-Ymmm and ASM (selectivity up to 68% at 100% conversion of aniline), while the reaction on zeolites with microporous structure mainly gave N-phenyl-2-propanimine (selectivity up to 91%).