改性丝光沸石上甲醇胺化的研究——水汽处理对沸石性能的影响

采用哟饱和中毒，ＮＨ３－ＴＰＤ、静态吸附、ＩＲ、ＸＲＤ和分子探针反应等方法，研究了用于甲醇胺化反应的改性丝光沸石催化剂性质，结果发现，丝光沸石水汽处理脱吕后的孔道结构基本不变，晶胞的收缩和非骨架铝在孔道内的沉积，不足以严重限制甲醇胺化产物三甲胺在孔道内的进出；且在改性后，由于非骨架非孔道内的沉积，分子筛内表面的微环境发生了变化，致使有些活性位不利于三 的吸附和生成，从而有利于进一步提高目的产物二甲     

甲胺在择形分子筛催化剂上的选择性合成

考察了同晶置换改性丝光沸石和金属表面活性改性ＨＺＳＭ－５对甲醇胺化反应的催化性能，发现两种改性方法都可以降低三甲胺（ＴＭＡ）选择性，提高一甲胺（ＭＭＡ）与二甲胺（ＤＭＡ）的选择性，两种方法都是通过分子筛外表面改性以实现择形性调变的，同晶置换改性可使丝光沸石的强酸性发生显著变化，而强Ｂ酸中心是丝光沸石催化胺化反应的活性中心。     

化学蒸气沉积硅氧化合物调变HZSM－5沸石的研究

本文研究了正硅酸乙酯分别在无胺法和有胺法制得的ＨＺＳＭ－５沸石上的沉积过程，并用吸附，ＮＨ３－ＴＰＤ及异丙醇探针反应等手段表征了沉积后的样品，发现沉积仅在外表面上进行，可使孔口变小但不影响孔道内性质，显示有对于二甲苯分子的择形吸附能力，且在甲苯甲醇烷基化反应和二甲苯异构化反应中表现出良好的择形催化性能．     

碱金属丝光沸石的表征及对甲胺合成反应的性能

对不同碱金属含量和不同温度水汽处理的丝光沸石样品，用ＸＲＤ和ＩＲ进行了物性表征，对其中某些样品以甲醇与氟合成甲胺反应用连续反应一在线分析进行了考察．水汽处理后，沸石发生骨架脱铝并保持很高的结晶度，其Ｂ酸总酸量及强酸量均剧降；甲醇转化活性反而提高，二甲胺选择性也显著提高，三甲胺选择性降至很低．表明过多、过强的酸性中心于本反应无益．此外，沸石经水汽处理后发生多种变化，产生了良好的择形催化效应．     

化学蒸气沉积硅氧化合物调变HZSM-5沸石的研究

本文研究了正硅酸乙酯分别在无胺法和有胺法制得的ＨＺＳＭ－５沸石上的沉积过程，并用吸附，ＮＨ３－ＴＰＤ及异丙醇探针反应等手段表征了沉积后的样品，发现沉积仅在外表面上进行，可使孔口变小但不影响孔道内性质，显示有对于二甲苯分子的择形吸附能力，且在甲苯甲醇烷基化反应和二甲苯异构化反应中表现出良好的择形催化性能。     

硅烷对HZSM－5沸石分子筛的改性研究Ⅱ．硅烷化改性对HZSM－5表面酸性、吸附性能和催化性能的影响

以硅烷气体作为改性剂，对ＨＺＳＭ－５沸石进行了改性研究，并用ＮＨ＿３－ＴＰＤ，表面羟基和吡啶吸附态红外光谱的手段表征了改性样品。发现随着硅烷化程度的加深，强酸和弱酸开始降低，硅烷化程度ｗ％＞１．８３％后，酸性基本保持不变，这时改性只起到明显的缩孔作用。通过对改性沸石探针分子吸附行为的研究分析得知，硅烷化开始时，硅烷分子进入了孔道内，与内表面羟基反应，致使部分孔道堵塞，孔道变窄。硅烷化程度ｗ％＞１．８３％后，硅烷分子扩散进孔内受阻，转换到与外表面羟基反应，只起到改性外表面缩小孔径的作用。这种改性的ＨＺＳＭ－５沸石对甲醇胺化反应的活性和选择性都有很好的促进作用。     

无胺法合成高硅丝光沸石的表征

采用XRD、SEM、FT-IR、MAS NMR等表征手段, 对以氟离子为结构导向剂无胺法合成的高硅丝光沸石进行了表征. 结果表明: 高硅丝光沸石结构属立方晶系, 晶胞参数小于传统低硅丝光沸石, 但b、c值要比相近硅铝比非氟体系合成的丝光沸石样品的大; 样品形貌及粒径与其硅铝比有关, 表明晶化条件对产物形貌及粒径均有影响; 随硅铝比的增大, FT-IR光谱中450、544、1053 cm-1谱带向高频移动, 720 cm-1谱带强度减弱, 表明骨架中铝减少而硅增多; 采用含氟无胺体系合成高硅丝光沸石时基本上不会产生非骨架铝.     

SDY型沸石的浸取处理及其对催化性能的影响

分别用Ｎａ２Ｈ２ＥＤＴＡ、Ｈ４ＥＤＴＡ和Ｈｃｌ对ＳＤＹ型沸石的非骨架铝进行了浸取处理，并应用化学分析、ＸＲＤ、高真空苯吸附、低温Ｎ２吸附、ＮＨ３－ＴＰＤ和正庚烷裂解脉冲微型反应等物理和化学实验技术对浸取前后样品的结构、酸性和催化性能进行了研究。发现Ｎａ２Ｈ２ＥＤＴＡ能选择地浸取沉积于沸石微孔和二次孔中的非骨架铝碎片，且不损伤沸石骨架，浸取出部分非骨架铝后的样品，其正庚烷裂解和抗氮性能均有所提高。     

氯硅烷改性对Y沸石结构的影响

用２９Ｓｉ，２７ＡｌＭＡＳＮＭＲ，ＸＲＤ及化学分析法研究了氯硅烷改性Ｙ沸石的结构及组成变化，结果表明改性过程伴有脱铝和补硅作用，并同时有大量非骨架铝碎片形成．非骨架铝有两类，一类是２７ＡｌＭＡＳＮＭＲ可测的，另一类是不可测的．改性沸石的酸性可能来源于非骨架铝碎片．对各催化剂上甲苯歧化反应的考察表明，由于改性沸石酸度适中，是较ＨＹ沸石优良的催化剂．     

碱金属丝光沸石的表征及对甲胺合成的反应的性能

对不同碱金属含量和不同温度水汽处理的丝光沸石样品，用ＸＲＤ和ＩＲ进行了物性表征，对其中某些样品以甲醇与氨合成甲胺反应用连续反应－在线分析进行了考察。水汽处理后，沸石发生骨架脱铝并保持很结晶度，其Ｂ酸总酸量及强酸量均剧降；甲醇转化活性反而提高，二甲胺选择性也显著提高，三甲胺选择性降至很低。表明过多、过强的酸性中心于本反应无益。此外，沸石经汽处理后发生多种变化，产生了良好的择形催化效应。     

水热处理对MCM-22催化剂酸性、孔结构及甲苯/甲醇烷基化性能的影响

采用XRD, NH3-TPD, IR和低温氮气吸附等方法研究了分别以纯水蒸气和质量分数为6％的氨水蒸气处理MCM-22分子筛催化剂后, 其酸性和孔结构的变化, 并以甲苯、甲醇烷基化为探针反应考察了催化剂的催化性能. 研究结果表明, 在两种不同介质中和处理温度不高于400 ℃条件下, 催化剂的总酸量变化不大, 强酸中心有所增加; 处理温度高于500 ℃后, 催化剂的总酸量明显下降, 强酸中心基本消失; 经水热处理后, MCM-22分子筛催化剂中形成了孔径不均匀的二次孔, 平均孔径增大. 随着处理温度的提高, 催化剂的活性降低, 对二甲苯和邻二甲苯的选择性上升. 经500 ℃纯水蒸气处理5 h的MCM-22催化剂, 具有适宜的酸强度和酸类型分布, 有利于甲苯甲醇烷基化反应的进行, 且催化剂维持了较高的催化活性并具有一定的对位选择性(甲苯转化率和对二甲苯选择性分别29.22％和42.16％).     

Structure and molecular conformation of tussah silk fibroin films treated with water–methanol solutions: Dynamic mechanical and thermomechanical behavior

The thermal response of tussah (Antheraea pernyi) silk fibroin films treated with different water–methanol solutions at 20°C was studied by means of dynamic mechanical (DMA) and thermomechanical (TMA) analyses as a function of methanol concentration and treatment time. The DMA curves of α-helix films (treated with ≥80% v/v methanol for 2 min and 100% methanol for 30 min) showed the sharp fall of storage modulus at about 190°C, and the loss peak in the range 207–213°C. The TMA curves were characterized by a thermal shrinkage at 209–211°C, immediately followed by an abrupt extension leading to film failure. Both storage and loss modulus curves significantly shifted upwards for β-sheet films, obtained by treatment with ≤60% methanol for 30 min. The loss peak exhibited a maximum at 236°C. Accordingly, the TMA shrinkage at above 200°C disappeared. The films broke beyond 330°C, failure being preceded by a broad contraction step. Intermediate DMA and TMA patterns were observed for the other solvent-treated films. The loss peak shifted to higher temperature (219–220°C), and a minor loss modulus component appeared at about 230°C. This coincided with the onset of a plateau region in the storage modulus curve. The TMA extension–contraction events in the range 200–300°C weakened, and the samples displayed a final broad contraction (peak temperature 326–338°C) before breaking. The DMA and TMA response of these films was attributed to partial annealing by solvent treatment, which resulted in the formation of nuclei of β-sheet crystallization within the film matrix. The increased thermal stability was probably due to the small β-sheet crystals formed, which acted as high-strength junctions between adjacent random coil and α-helix domains. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2717–2724, 1998     

Pathways of Methane Transformation over Copper‐Exchanged Mordenite as Revealed by In Situ NMR and IR Spectroscopy

The reaction of methane with copper‐exchanged mordenite with two different Si/Al ratios was studied by means of in situ NMR and infrared spectroscopies. The detection of NMR signals was shown to be possible with high sensitivity and resolution, despite the presence of a considerable number of paramagnetic Cu^II species. Several types of surface‐bonded compounds were found after reaction, namely molecular methanol, methoxy species, dimethyl ether, mono‐ and bidentate formates, Cu^I monocarbonyl as well as carbon monoxide and dioxide, which were present in the gas phase. The relative fractions of these species are strongly influenced by the reaction temperature and the structure of the copper sites and is governed by the Si/Al ratio. While methoxy species bonded to Brønsted acid sites, dimethyl ether and bidentate formate species are the main products over copper‐exchange mordenite with a Si/Al ratio of 6; molecular methanol and monodentate formate species were observed mainly over the material with a Si/Al ratio of 46. These observations are important for understanding the methane partial oxidation mechanism and for the rational design of the active materials for this reaction.     

Pathways of Methane Transformation over Copper-Exchanged Mordenite as Revealed by In Situ NMR and IR Spectroscopy

The reaction of methane with copper-exchanged mordenite with two different Si/Al ratios was studied by means of in situ NMR and infrared spectroscopies. The detection of NMR signals was shown to be possible with high sensitivity and resolution, despite the presence of a considerable number of paramagnetic Cu^II species. Several types of surface-bonded compounds were found after reaction, namely molecular methanol, methoxy species, dimethyl ether, mono- and bidentate formates, Cu^I monocarbonyl as well as carbon monoxide and dioxide, which were present in the gas phase. The relative fractions of these species are strongly influenced by the reaction temperature and the structure of the copper sites and is governed by the Si/Al ratio. While methoxy species bonded to Brønsted acid sites, dimethyl ether and bidentate formate species are the main products over copper-exchange mordenite with a Si/Al ratio of 6; molecular methanol and monodentate formate species were observed mainly over the material with a Si/Al ratio of 46. These observations are important for understanding the methane partial oxidation mechanism and for the rational design of the active materials for this reaction.     

Enzyme-like specificity in zeolites: a unique site position in mordenite for selective carbonylation of methanol and dimethyl ether with CO

The mechanism of methanol carbonylation at different positions of zeolite MOR is investigated by quantum-chemical methods in order to discover which are the active sites that can selectively catalyze the desired reaction. It is shown that when methanol carbonylation competes with hydrocarbon formation, the first reaction occurs preferentially within 8MR channels. However, the unique selectivity for the carbonylation of methanol and dimethyl ether in mordenite is not only due to the size of the 8MR channel: neither process occurs equally at the two T3-O31 and T3-O33 positions. We show that only the T3-O33 positions are selective and that this selectivity is due to the unusual orientation of the methoxy group in relation to the 8MR channel (parallel to the cylinder axis). Only in this situation does the transition state for the attack of CO fit perfectly in the 8MR channel, while the reaction with methanol or DME is sterically impeded. This result explains why T3-O31, while also located in the 8MR channel of mordenite, is not as selective as the T3-O33 position and why ferrierite, although it contains 8MR channels, is less selective than mordenite. The competing effect of water is explained at the molecular level, and the molecular microkinetic reaction model has been established.     

SELECTIVE SYNTHESIS OF DIMETHYLAMINE OVER RARE EARTH MODIFIED MORDENITES

研究了稀土（Ｃｅ、Ｇｄ和Ｙ）改性丝光沸石用作甲醇胺化催化剂在常压固定床反应器中选择性合成二甲胺的催化性能。结果表明，稀土阳离子交换改性能改善丝光沸石的催化性能。丝光沸石经０．１ｍｏｌ／ＬＣｅ４＋溶液处理，与膨润土成型，再于６００℃下焙烧２～３ｈ，这样制得的催化剂在常压４００℃时的活性及二甲胺选择性分别达到９９．８％和５０．３％。此外，详细探讨了不同改性及制备条件对催化剂催化性能及机械强度的影响。     

碱处理丝光沸石的表征及其催化合成乙基叔丁基醚的性能

 研究了碱处理对丝光沸石物相、酸性质和催化合成乙基叔丁基醚(ETBE)性能的影响,并采用XRD,NH3-TPD,吡啶吸附的IR,SEM和N2吸附等方法对其进行了表征. 结果表明,碱处理含有模板剂的丝光沸石的相对结晶度、酸量、比表面积和孔容都增大. 碱处理已脱除模板剂的丝光沸石的相对结晶度、酸量、比表面积和孔容都减小. 碱处理含有模板剂的丝光沸石催化合成ETBE的活性明显高于碱处理已脱除模板剂的丝光沸石,在80 ℃左右即可达到最高活性点,其催化异丁烯的最高转化率为58%,比未经碱处理样品上异丁烯的最高转化率高约13%.     

ZSM-5-SBA-15复合分子筛制备及甲苯甲醇烷基化性能研究

采用后合成法制备了ZSM-5-SBA-15复合分子筛,通过XRD、FT-IR、BET、NH₃-TPD及吡啶红外等手段表征催化剂的性质。结果表明,ZSM-5-SBA-15既具有微孔结构又具有介孔结构。吡啶吸附和NH₃吸脱附实验结果表明,ZSM-5微孔分子筛的引入使SBA-15介孔分子筛的酸性增强,但与ZSM-5相比,ZSM-5-SBA-15复合分子筛的酸性位没有改变,酸强度有一定的减弱。用固定床评价了该复合分子筛甲苯甲醇烷基化反应的催化性能。结果表明,与常规ZSM-5相比,ZSM-5-SBA-15表现出了较高的对位选择性。