高硅Y沸石的研制及吸附热力学性质

Ｙ沸石用ＬｉＣｌ溶液交换得ＬｉＮａＹ沸石,再经ＳｉＣｌ４气相同晶取代进行脱铝补硅,获得高结晶度的高硅Ｙ沸石,硅铝比可大于１００［１］．在脱铝过程中,随着硅铝比的升高其孔结构和表面性质均发生变化,直接关联到Ｙ沸石在炼油中的催化裂化性能．通过对不同大小、结?..     

SAPO－34分子筛表面酸性质的研究

以水热合成法制备了三个具有不同硅磷铝组成的硅磷酸铝分子筛ＳＡＰＯ－３４样品，采用红外光谱（ＩＲ）和氨法程序升温脱附（ＴＰＤ）两种方法考察了它们的表面酸性质。红外谱图中的３６００ｃｍ－１和３６２１ｃｍ－１谱峰归属于处于ＳＡＰＯ－３４分子筛结构中不同位置的两种桥联羟基（Ｓｉ－ＯＨ－Ａｌ）的振动。ＮＨ３－ＩＲ测定结果显示，这两种羟基具有较强的Ｂ酸特性，并且是分子筛酸性的主要来源；而分子筛具有的Ｌ酸中心的酸性较弱。比较三个样品的ＮＨ３－ＴＰＤ、ＮＨ_３－ＩＲ和骨架组成后发现，ＳＡＰＯ－３４的酸性受其骨架硅含量的强烈影响：当Ｓｉ／Ａｌ摩尔比小于１时，酸性随硅含量增高而变弱；当Ｓｉ／Ａｌ摩尔比大于１时，酸性将随硅含量增高而变强。     

载铂铝交联蒙脱土（Pt／Al－CLM）的结构稳定化作用与其n－C_8芳构化性能的关系

利用ＸＲＤ、ＤＴＡ、ＩＲ考察了预焙烧对铝交联蒙脱土（Ａｌ－ＣＬＭ）结构的稳定化作用及引入铂对稳定Ａｌ－ＣＬＭ结构的协同效应；用加压连续流动微反装置研究了Ｐｔ／Ａｌ－ＣＬＭ的ｎ－Ｃ_８芳构化性能与其结构稳定性的关系。结果表明：经４００－５００℃的高温预焙烧可使Ａｌ－ＣＬＭ在浸铂过程中保持较高的层结构有序度和规整性，相应保持较大的层间域尺度，对Ａｌ－ＣＬＭ的结构具有稳定作用；引入的铂与Ａｌ－ＣＬＭ的四面体片发生相互作用，可抑制硅氧四面体的扭曲旋转，从而阻抑八面体结构羟基的脱除，具有稳定结构羟基的作用；而Ｐｔ／Ａｌ－ＣＬＭ的ｎ－Ｃ_８芳构化Ｃ_８芳烃收率与其结构的完整性、有线性、相关性。     

稀土氧化物固体碱催化剂的表面性质Ⅰ.稀土氧化物表面活性中心的表征

采用ＴＰＤ－ＭＳ，ＩＲ等技术研究了Ｌａ２Ｏ３，Ｙ２Ｏ３，Ｎｄ２Ｏ３，ＣｅＯ２及参照氧化物Ａｌ２Ｏ３ＺｒＯ２，ＭｇＯ表面的酸碱性，氧活性及表面羟基，结果表明，上述稀土氧化物表面上不仅存在着两种碱中心，还有酸中心存在，且其表面都存在的活性氧中心表面的性质同碱土氧化物ＭｇＯ类似，但与Ａｌ２Ｏ３ＺｒＯ２等有较大差别。     

稀土氧化物固体碱催化剂的表面性质Ⅰ．稀土氧化物表面活性中心的表征

采用ＴＰＤ－ＭＳ，ＩＲ等技术研究了Ｌａ２Ｏ３，Ｙ２Ｏ３，Ｎｄ２Ｏ３，ＣｅＯ２及参照氧化物Ａｌ２Ｏ３，ＺｒＯ２，ＭｇＯ表面的酸碱性，氧活性及表面羟基．结果表明，上述稀土氧化物表面上不仅存在着两种碱中心，还有酸中心存在，且其表面都存在活性氧中心，表面的性质同碱土氧化物ＭｇＯ类似，但与Ａｌ２Ｏ３，ＺｒＯ２等有较大差别     

氟硅酸铵处理对γ-Al2O3负载NiW催化剂性质的影响

应用ＩＲ，ＸＰＳ，ＴＰＲ，ＮＯ和ＣＯ２吸附及脉冲微反等技术研究了氟硅酸铵处理前后β－Ａｌ２Ｏ３及负载ＮｉＷ催化剂的表面性质，探讨了其改性机理地催化剂活性相的影响，结果表明，经氟硅酸铵处理后，γ－Ａｌ２Ｏ３表面的不饱和四面体空位及其四配位Ａｌ＾３＋上的强碱性羟基均明显减少，改变了γ－Ａｌ２Ｏ３表面的酸碱性和Ｎｉ＾２＋在γ－Ａｌ２Ｏ３表面的分布，使ＮｉＯ倾向分布于γ－Ａｌ２Ｏ３的八面体空位，过量的氟硅     

K2O修饰γ—Al2O3的表面性能研究

本文利用ＥＰＭＡ，ＸＰＳ和ＦＴＩＲ等物理方法，研究了浸渍Ｋ２Ｏ以后的γ－Ａｌ２Ｏ３的表面组成，表面羟基性质，表面酸碱性以及表面各元素电子结构能的变化。实验结果表明，γ－Ａｌ２Ｏ３羟Ｋ２Ｏ修饰以后，表面Ｋ／Ａｌ比大于本体Ｋ／Ａｌ比，Ｋ２Ｏ富集－Ａｌ２Ｏ３的表面上；Ｋ２Ｏ在表面上起到的抑制酸性，增强碱性包括羟基碱性的作用。     

国产硅藻土结构的研究

系统地研究了硅藻土结构, 发现除浙江白土表面具有双生的硅羟基外, 其它只有连生的与孤立的硅羟基; 经IR谱证明, 其内部尚有Si-O与Al-O振动, 酸洗或焙烧都能使硅藻体的孔径、孔径分布和结构发生改变; 经焙烧后, 结构均发生改变, 其自由水消失, 束缚水逐渐减少; 焙烧达1150℃时, 原组成无定形二氧化硅则晶化为α-方石英, 除吉林土具有一级孔洞, 云南土具有三级孔洞外, 本文中其它硅藻土均有二级孔洞。     

Raney Cu—Nd 催化剂表面性质的表征

采用ＢＥＴ和ＴＥＭ表征手段对不同组成的ＣｕＡｌＮｄ合金及其碱抽提产物ＲａｎｅｙＣｕＮｄ催化剂的表面织构和孔结构进行了表征。结果表明，ＲａｎｅｙＣｕ催化剂为单孔型催化剂，ＲａｎｅｙＣｕＮｄ为双孔型催化剂，小孔为狭缝状孔道，大孔为两端开放的直通型孔道。ＣｕＡｌ２物相脱Ａｌ形成大孔，Ｃｕ４ＮｄＡｌ８物相脱Ａｌ形成小孔。随着抽Ａｌ程度的加深，比表面积和孔容增大，孔径ｒｐ却呈减小的趋势。甲酸甲酯氢解反应结果表明，抽提部分Ａｌ的催化剂，其甲酸甲酯转化率均低于ＲａｎｅｙＣｕ；完全抽提Ａｌ的催化剂，低Ｎｄ含量样品的活性均大于ＲａｎｅｙＣｕ，适量加入Ｎｄ对提高活性是有利的。对ＲａｎｅｙＣｕＮｄ催化性能的影响因素主要是Ｎｄ元素的添加量和铜活性位的数目。     

K_2O修饰γ－Al_2O_3的表面性能研究

本文利用ＥＰＭＡ、ＸＰＳ和ＦＴＩＲ等物理方法，研究了浸渍Ｋ２Ｏ以后的γ－Ａｌ２Ｏ３的表面组成、表面羟基性质、表面酸碱性以及表面各元素电子结合能的变化。实验结果表明，γ－Ａｌ２Ｏ３经Ｋ２Ｏ修饰以后，表面Ｋ／Ａｌ比大于本体Ｋ／Ａｌ比，Ｋ２Ｏ富集在γ－Ａｌ２Ｏ３的表面上；Ｋ２Ｏ在表面上起到了抑制酸性，增强碱性包括羟基碱性的作用；表面碱性中心种类增多、碱性增强、分布增宽的主要原因是表面氧的电负性增强和铝在一定程度上的还原。     

Facile preparation of hierarchically porous carbon using diatomite as both template and catalyst and methylene blue adsorption of carbon products

Hierarchically porous carbons were prepared using a facile preparation method in which diatomite was utilized as both template and catalyst. The porous structures of the carbon products and their formation mechanisms were investigated. The macroporosity and microporosity of the diatomite-templated carbons were derived from replication of diatom shell and structure-reconfiguration of the carbon film, respectively. The macroporosity of carbons was strongly dependent on the original morphology of the diatomite template. The macroporous structure composed of carbon plates connected by the pillar- and tube-like macropores resulted from the replication of the central and edge pores of the diatom shells with disk-shaped morphology, respectively. And another macroporous carbon tubes were also replicated from canoe-shaped diatom shells. The acidity of diatomite dramatically affected the porosity of the carbons, more acid sites of diatomite template resulted in higher surface area and pore volume of the carbon products. The diatomite-templated carbons exhibited higher adsorption capacity for methylene blue than the commercial activated carbon (CAC), although the specific surface area was much smaller than that of CAC, due to the hierarchical porosity of diatomite-templated carbons. And the carbons were readily reclaimed and regenerated.     

Flocculation of diatomite by methylated egg albumin

A common and inexpensive protein, egg albumin, was applied to the solid-liquid separation or flocculation of diatomite. Egg albumin was methylated in a 0.05 M HCl methyl alcohol solution at room temperature. About 90% of the carboxylic groups of egg albumin could be methylated within 24 h. The adsorption of egg albumin onto diatomite at pH 6.8 was remarkably enhanced by methylation. The adsorption constant of methylated egg albumin to diatomite at 30 degrees C was about 100-fold larger than that of native egg albumin; however, the adsorption constant of methylated egg albumin decreased to about 1/100 with temperature decreasing from 30 to 6 degrees C. The saturated adsorption amount of egg albumin was also increased by the methylation. The flocculating ability of methylated egg albumin was examined with a diatomite suspension at 6 and 30 degrees C in the pH range from pH 2 to 11. The diatomite suspension was effectively flocculated by the addition of small amounts of methylated egg albumin (only 0.5-1 wt% against diatomite) over a wide pH range from pH 3 to 10.     

Bulgarian natural diatomites: modification and characterization

Natural Bulgarian diatomite modified by oxidation with sulfuric acid and H₂O₂ or by coating with manganese oxide was characterized considering its chemical composition, surface area, pore volume, and structure. Modified diatomites displayed larger surface area and pore volumes in comparison with untreated natural diatomite, which favored their sorption behavior. Sorption properties of diatomites towards Fe³⁺, Pb²⁺, Cu²⁺, Cd²⁺, Mn²⁺, Ni²⁺, Co²⁺, Cr³⁺, Pd²⁺, Ca²⁺, and Mg²⁺ were investigated and their sorption capacities were determined. Sorption properties of manganese oxide-modified diatomite were superior to those of diatomite modified by oxidation. Owing to its high sorption capacity towards Co²⁺, Ni²⁺, Pb²⁺, Cr³⁺, Fe²⁺, Cu²⁺, and Cd²⁺, the manganese oxide-modified diatomite is a promising low-cost sorbent for selective removal of milligram amounts of these toxic metal ions from contaminated water.     

国产硅藻土吸附尿激酶机理的研究

在常温下, 尿激酶在浙江土和吉林土表面的吸附等温线分别为V型和II型; 焙烧后两者皆转为III型。吸附等温线类型与硅藻土表面结构、孔结构、表面ζ电位有关。在400℃焙烧的硅藻土等电点值最低, 吸附量最大; 改性后, 吸附量也发生改变。本文还测定了尿激酶在硅藻土表面的吸附形态, 其吸附等温线方程符合0/(1-0)=(Kc)^1/β, 并讨论了平衡常数K和尿激酶吸附功能链段数β随温度的变化。     

Hydroxyl‐Mediated Non‐oxidative Propane Dehydrogenation over VOx/γ‐Al2O3 Catalysts with Improved Stability

Supported vanadium oxides are one of the most promising alternative catalysts for propane dehydrogenation (PDH) and efforts have been made to improve its catalytic performance. However, unlike Pt‐based catalysts, the nature of the active site and surface structure of the supported vanadium catalysts under reductive reaction conditions still remain elusive. This paper describes the surface structure and the important role of surface‐bound hydroxyl groups on VO_x / γ‐Al₂O₃ catalysts under reaction conditions employing in situ DRIFTS experiments and DFT calculations. It is shown that hydroxyl groups on the VO_x /Al₂O₃ catalyst (V?OH) are produced under H₂ pre‐reduction, and the catalytic performance for PDH is closely connected to the concentration of V?OH species on the catalyst. The hydroxyl groups are found to improve the catalyst that leads to better stability by suppressing the coke deposition.     

Enhanced Dye Adsorption by Microemulsion-Modified Calcined Diatomite (μE-CD)

This study attempted to improve the adsorption performance of calcined diatomite for the removal of colour from wastewaters through modification with microemulsions. The surface area, pH_ZPC, Fourier transform infrared (FTIR) of calcined diatomite and μE-CD were studied. It is found that an increase in the BET surface area, pH_ZPC and total pore volume after modification was obtained. A decrease in average pore volume was observed after modification. This suggests that the pore opening deceased to be in the micro- and meso-pore region hence the adsorption capacity for the modified adsorbent will be enhanced by reducing the escaping of dye molecules. The influence of concentration, pH and particle size on the adsorption capacities of methylene blue (MB), hydrolysed reactive black (RB) and hydrolysed reactive yellow (RY) was investigated. It was concluded from FTIR and pH analysis that the predominant mechanism of RY molecules onto μE-CD is by an electrostatic attraction between the carboxylate anion and the dye. In the case of MB and RB, the adsorption mechanism could be a combination of different mechanisms such as electrostatic attraction, capturing by microemulsion micelles in the pores of the calcined diatomite or the hydrophobic attraction. The adsorption capacities were higher than unmodified calcined diatomite. In the case of adsorption of MB molecules, a high adsorption capacity onto μE-CD was obtained.     

酸法纳米纤维素模板剂合成介孔TiO2及光催化活性

以生物可再生资源的酸法纳米纤维素为模板剂,四氯化钛为钛源,采用液相水解-沉淀法制备了具有介孔结构的TiO2光催化剂。采用低温N2物理吸附-脱附、透射电镜(TEM)、X射线衍射(XRD)、热重-量热扫描(TG/DSC)、傅里叶变换红外(FTIR)、X射线光电子能谱(XPS)等对介孔TiO2进行了表征,并以甲基橙为模型物,考察了介孔TiO2光催化活性。结果表明,以酸法纳米纤维素为模板剂合成的TiO2光催化活性显著提高,且具有良好的孔隙结构,平均孔径5.03 nm、总孔容积0.35 cm3.g-1、比表面积192m2.g-1;纤维素模板剂合成的TiO2表面羟基数量降低;纤维素长链分子结构之间的羟基与TiO2表面羟基的键合,可有效限制TiO2前驱体的生长和团聚,并抑制锐钛矿相TiO2向金红石相转变。     

Effects of inherent/enhanced solid acidity and morphology of diatomite templates on the synthesis and porosity of hierarchically porous carbon

The inherent or enhanced solid acidity of raw or activated diatomite is found to have significant effects on the synthesis of hierarchically porous diatomite-templated carbon with high surface area and special porous structure. The solid acidity makes raw/activated diatomite a catalyst for the generation of porous carbon, and the porous parameters of the carbon products are strongly dependent on the solid acidity of diatomite templates. The morphology of diatomite also dramatically affects the textural structure of porous carbon. Two types of macroporous structures in the carbon product, the partially solid pillars and the ordered hollow tubes, derive from the replication of the central and the edge pores of diatom shell, respectively. The hierarchically porous carbon shows good capability for the adsorption of solvent naphtha and H(2), enabling potential applications in adsorption and gas storage.     

Influence of surface free energy on the adhesion of marine benthic diatom Nitzschia closterium MMDL533

The self-assembled monolayers (SAMs) with gradient surface free energies were prepared by surface grafting of a binary mixture of methyl and vinyl terminated trimethoxysilanes on hydrophilic glass slides followed by in situ oxidation of vinyl groups into carboxyl groups. Characterized by contact angles, the SAMs combined with freshly cleaned glass slides bearing hydroxyl groups were used to study the adhesion behavior of marine benthic diatom Nitzschia closterium MMDL533. The attachment densities were much higher on hydrophobic CH₃-SAMs and lower on mixed SAMs with surface free energy of 40.1–50.4 mJ/m². More gregarious adhesion had been found on hydrophobic CH₃-SAMs. The percentage removal was in a narrow range of 63–80% on the engineered surfaces and was much lower with a value of 54% on the hydrophilic slides. Our studies have revealed some subtle but interesting differences in attachment and adhesion from the features reported for these benthic species, indicating the possible links to different diatom species.