Sulfated titania mediated regioselective nitration of phenol in solid state

Titania, sulfated titania and chromium loaded sulfated titania were prepared by sol–gel method and characterized using different technique. Phenol is nitrated regioselectively by nitric acid using chromium loaded sulfated titania catalysts. A remarkable ortho selectivity is observed in solid state nitration to yield exclusively ortho-nitrophenol. Compared to the conventional process, phenol nitration over solid acid catalyst is a clean and environment friendly process. Catalytic activity well correlates with the Brönsted acid sites of these catalysts.

Pyrolysis and gasification of biomass and acid hydrolysis residues

This research was carried for an EC supported project that aimed to produce ethyl levulinate as a diesel miscible biofuel from biomass by acid hydrolysis. The objective of this research was to explore thermal conversion technologies to recover further diesel miscible biofuels and/or other valuable products from the remaining solid acid hydrolysis residues (AHR). AHR consists of mainly lignin and humins and contains up to 80% of the original energy in the biomass. Fast pyrolysis and pyrolytic gasification of this low volatile content AHR was unsuccessful. However, successful air gasification of AHR gave a low heating value gas for use in engines for power or heat with the aim of producing all the utility requirements in any commercial implementation of the ethyl levulinate production process. In addition, successful fast pyrolysis of the original biomass gave organic liquid yields of up to 63.9 wt.% (dry feed basis) comparable to results achieved using a standard hardwood. The fast pyrolysis liquid can be used as a fuel or upgraded to biofuels. A novel molybdenum carbide catalyst was tested in fast pyrolysis to explore the potential for upgrading. Although there was no deoxygenation, some bio-oil properties were improved including viscosity, pH and homogeneity through decreasing sugars and increasing furanics and phenolics. AHR gasification was explored in a batch gasifier with a comparison with the original biomass. Refractory and low volatile content AHR gave relatively low gas yields (74.21 wt.%), low tar yields (5.27 wt.%) and high solid yields (20.52 wt.%). Air gasification gave gas heating values of around 5MJ/NM3, which is a typical value, but limitations of the equipment available restricted the extent of process and product analysis. In order to improve robustness of AHR powder for screw feeding into gasifiers, a new densification technique was developed based on mixing powder with bio-oil and curing the mixture at 150°C to polymerise the bio-oil.

Can surface energy measurements predict the impact of catalyst hydrophobicity upon fatty acid esterification over sulfonic acid functionalised periodic mesoporous organosilicas?

Sulfonic acid functionalised periodic mesoporous organosilicas (PrSO3 H-PMOs) with tunable hydrophobicity were synthesised via a surfactant-templating route, and characterised by porosimetry, TEM, XRD, XPS, inverse gas chromatography (IGC) and ammonia pulse chemisorption. IGC reveals that incorporation of ethyl or benzyl moieties into a mesoporous SBA-15 silica framework significantly increases the non-specific dispersive surface energy of adsorption for alkane adsorption, while decreasing the free energy of adsorption of methanol, reflecting increased surface hydrophobicity. The non-specific dispersive surface energy of adsorption of PMO-SO3H materials is strongly correlated with their activity towards palmitic acid esterification with methanol, demonstrating the power of IGC as an analytical tool for identifying promising solid acid catalysts for the esterification of free fatty acids. A new parameter [-ΔGCNP-P], defined as the per carbon difference in Gibbs free energy of adsorption between alkane and polar probe molecules, provides a simple predictor of surface hydrophobicity and corresponding catalyst activity in fatty acid esterification. © 2014 Elsevier B.V.

Hierarchical macroporous-mesoporous SBA-15 sulfonic acid catalysts for biodiesel synthesis

Hierarchical macroporous-mesoporous SBA-15 silicas have been synthesised via dual-templating routes employing liquid crystalline surfactants and polystyrene beads. These offer high surface areas and well-defined, interconnecting macro- and mesopore networks with respective narrow size distributions around 300 nm and 3-5 nm for polystyrene:tetraethoxysilane ratios ≥2:1. Subsequent functionalisation with propylsulfonic acid yields the first organized, macro-mesoporous solid acid catalyst. The enhanced mass transport properties of these new bi-modal solid acid architectures confer significant rate enhancements in the transesterification of bulky glyceryl trioctanoate, and esterification of long chain palmitic acid, over pure mesoporous analogues. This paves the way to the wider application of hierarchical catalysts in biofuel synthesis and biomass conversion. © 2010 The Royal Society of Chemistry.

Zr-containing hybrid organic-inorganic mesoporous materials:hydrophobic acid catalysts for biodiesel production

Zirconium-containing periodic mesoporous organosilicas (Zr-PMOs) with varying framework organic content have been synthesized through a direct synthesis method. These materials display the excellent textural properties of the analogous inorganic solid acid Zr-SBA-15 material. However, the substitution of silica by organosilicon species provides a strong hydrophobic character. This substitution leads to meaningful differences in the environment surrounding the zirconium metal sites, leading the modification of the catalytic properties of these materials. Although lower metal incorporation is accomplished in the final materials, leading to a lower population of metal sites, hydrophobisation leads to an impressive beneficial effect on the intrinsic catalytic activity of the zirconium sites in biodiesel production by esterification/transesterification of free fatty acid -containing feedstock. Moreover, the catalytic activity of the highly hybridised materials is hardly affected in presence of large amounts of water, confirming their very good water-tolerance. This makes Zr-PMO materials interesting catalysts for biodiesel production from highly acidic water-containing feedstock. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tunable KIT-6 mesoporous sulfonic acid catalysts for fatty acid esterification

We report the first catalytic application of pore-expanded KIT-6 propylsulfonic acid (PrSO H) silicas, in fatty acid esterification with methanol under mild conditions. As-synthesized PrSO H-KIT-6 exhibits a 40 and 70% enhancement in turnover frequency (TOF) toward propanoic and hexanoic acid esterification, respectively, over a PrSO H-SBA-15 analogue of similar 5 nm pore diameter, reflecting the improved mesopore interconnectivity of KIT-6 over SBA-15. However, pore accessibility becomes rate-limiting in the esterification of longer chain lauric and palmitic acids over both solid acid catalysts. This problem can be overcome via hydrothermal aging protocols which permit expansion of the KIT-6 mesopore to 7 nm, thereby doubling the TOF for lauric and palmitic acid esterification over that achievable with PrSO H-SBA-15. © 2012 American Chemical Society.

High activity, templated mesoporous SO4/ZrO2/HMS catalysts with controlled acid site density for α-pinene isomerisation

Highly active mesoporous SO4/ZrO2/HMS (hexagonal mesoroporous silica) solid acid catalysts with tuneable sulphated zirconia (SZ) content have been prepared for the liquid phase isomerisation of α-pinene. The mesoporous HMS framework is preserved during the grafting process as evidenced by the X-ray diffraction (XRD) and porosimetry with all SO4/ZrO2/HMS materials possessing average pore-diameters ∼20 Å. XRD confirms the presence of a stabilized tetragonal phase of nanoparticulate ZrO2, with no evidence for zirconia phase separation or the formation of discrete crystallites, consistent with a uniform and highly dispersed SZ coating. The activity towards α-pinene isomerisation scales linearly with Zr loading, while the specific activities are an order of magnitude greater than attainable by conventional methodologies (∼1 versus 0.08 mol h−1 g Zr−1).

Hydrothermal saline promoted grafting of periodic mesoporous organic sulfonic acid silicas for sustainable FAME production

Hydrothermal saline promoted grafting of sulfonic acid groups onto SBA-15 and periodic mesoporous organic silica analogues affords solid acid catalysts with high acid site loadings (>2.5 mmol g-1 H+), ordered mesoporosity and tunable hydrophobicity. The resulting catalysts show excellent activity for fatty acid esterification and tripalmitin transesterification to methyl palmitate, with framework phenyl groups promoting fatty acid methyl esters production. (Chemical Equation Presented)

Synthesis and electrical properties of the (PVA)(0.7)(Kl)(0.3)center dot xH(2)SO(4) (0 <= x <= 5) polymer electrolytes and their performance in a primary Zn/MnO2 battery

Solid acid polymer electrolytes (SAPE) were synthesised using polyvinyl alcohol, potassium iodide and sulphuric acid in different molar ratios by solution cast technique. The temperature dependent nature of electrical conductivity and the impedance of the polymer electrolytes were determined along with the associated activation energy. The electrical conductivity at room temperature was found to be strongly depended on the amorphous nature of the polymers and H2SO4 concentration. The ac (100 Hz to 10 MHz) and dc conductivities of the polymer electrolytes with different H2SO4 concentrations were analyzed. A maximum dc conductivity of 1.05 x 10(-3) S cm(-1) has been achieved at ambient temperature for electrolytes containing 5 M H2SO4. The frequency and temperature dependent dielectric and electrical modulus properties of the SAPE were studied. The charge transport in the present polymer electrolyte was obtained using Wagner's polarization technique, which demonstrated the charge transport to be mainly due to ions. Using these solid acid polymer electrolytes novel Zn/SAPE/MnO2 solid state batteries were fabricated and their discharge capacity was calculated. An open circuit voltage of 1.758V was obtained for 5 M H2SO4 based Zn/SAPE/MnO2 battery. (C) 2010 Elsevier Ltd. All rights reserved.

K1-xLaxCa2-xNb3O10, a Layered Perovskite Series with Variable Interlayer Cation Density, and LaCaNb3O10, a Novel Layered Perovskite Oxide with No Interlayer Cations

A series of layered perovskite oxides of the formula K1-xLaxCa2-xNb3O10 for 0 < x ≤ 1.0 have been prepared. All the members are isostructural, possessing the structure of KCa2Nb3O10. The interlayer potassium ions in the new series can be ion-exchanged with protons to give H1-xLaxCa2-xNb3O10. The latter readily forms intercalation compounds of the formula (CnH2n+1NH3)1-x LaxCa2-xNb3O10, just as the parent solid acid HCa2Nb3O10. The end member LaCaNb3O10 containing no interlayer cations is a novel layered perovskite oxide, being a n = 3 member of the series An-1BnX3n+1.

Production of biodiesel from soapstock using an ion-exchange resin catalyst

The feasibility of biodiesel production from soapstock containing high water content and fatty matters by a solid acid catalyst was investigated. Soapstock was converted to high-acid acid oil (HAAO) by the hydrolysis by KOH and the acidulation by sulfuric acid. The acid value of soapstock-HAAO increased to 199.1 mg KOH/g but a large amount of potassium sulfate was produced. To resolve the formation of potassium sulfate, acid oil was extracted from soapstock and was converted to HAAO by using sodium dodecyl benzene sulfonate (SDBS). The maximum acid value of acid oil-HAAO was 194.2 mg KOH/g when the mass ratio of acid oil, sulfuric acid, and water was 10:4:10 at 2% of SDBS. In the esterification of HAAO using Amberylst-15, fatty acid methyl ester (FAME) concentration was 91.7 and 81.3% for soapstock and acid oil, respectively. After the distillation, FAME concentration became 98.1% and 96.7% for soapstock and acid oil. The distillation process decreased the total glycerin and the acid value of FAME produced a little.

BIODIESEL PRODUCTION FROM DIFFERENT FEEDSTOCKS IN PILOT SCALE SYSTEM

In this study, the preparations of biodiesel from three different feedstocks, including rapeseed oil, high acidified Chinese wood oil and trap grease, were carried out in a pilot scale of 200 t yr(-1) biodiesel production system. The optimum operating conditions for transesterification of rapeseed oil in plug flow reactor were found to be as follows: the catalyst dosage is 1.2 wt%; the retention time is about 17 min; the bed temperature is 65 degrees C; the oil/methanol ratio is 1:6; the content of methyl ester is 96.33% under these conditions. A kind of ion exchange resin, a solid acid catalyst, filled in the fixed bed reactor was used as the esterification catalyst for the pretreating of high acidified oil. The acid value of Chinese wood oil could be reduced from 7 to 0.8 mg KOH.g(-1) after 88 min, the optimum operating conditions were obtained as follow: molar ratio of methanol to oil is about 6:1, the temperature of the fixed bed, 65 degrees C and the retention time, about 88 min. Also a kind of acidified oil, namely trap grease, with the acid value being 114 mg KOH.g(-1) could be equally converted to a good biodiesel product through this system. Generally, the refined biodiesel product generated through this system could meet China #0 Biodiesel Standard, as well as Germany Biodiesel Standard for most indexes. It indicates that the designed process in this system has a good adaptability for different kinds of oil.

新型固体酸催化剂的设计制备及其性能研究

酸催化剂可以用来催化烃类裂解、重整、异构、烯烃水和、烷基化和酯化等重要化学反应，在石油炼制和石油化工领域有极其广泛的应用。与传统液体酸相比，新型固体酸催化剂具有容易与反应物和产物分离、易再生、不腐蚀反应器、环境污染少等优点，因此研究开发环境友好的新型固体酸催化剂成为国际上催化领域研究的热点。本论文研究新型固体酸催化剂的酸强度和延长催化剂使用寿命的方法，具有很高的工业实用价值和理论意义。 研究了固体酸催化剂在正己烷异构化和异丁醇脱水这两个反应的催化活性，结果显示：1）复合超强酸催化剂，2）Hβ及其负载催化剂，3）负载杂多酸，4）ZrO2·Bi2O3、ZrO2·CaO四类催化剂酸强度较高且强度大小为:1＞2≈3＞4。氢溢流的引入提高了Pt-SO42-/ ZrO2催化剂在反应中的催化活性,一定程度上弥补了酸强度的不足，也使一些原本没活性的催化剂有了一定的活性，如MOO3催化剂。 研究了异丁烷在12wt%V2O5/γ-Al2O3催化剂上脱氢制异丁烯的反应和异丁烯在50wt%HSiW/SiO2、Amberlyst-15和Amberlyst-35树脂催化剂上的迭代反应，均获得了较好的催化活性。 首次将催化剂表面的疏油性应用在酸催化领域，在硅胶负载的钨硅酸中掺杂不同含量聚四氟乙烯制备出具有一定疏油性的催化剂，用异丁烯迭代反应作为探针反应着重研究了催化剂表面的适当疏油性对催化剂的寿命和产物选择性的影响。结果显示催化剂表面的疏油性不仅提高了C8 =的选择性并且有效延长催化剂寿命。这主要是由于催化剂表面具有适当的疏油性，反应的中间产物C8=易于从具有疏油性的表面脱附，减少了C8=继续在催化剂表面进行连续反应生成C12=和C16=的机会，因此提高了C8=的选择性。这可能促进了更高的产物选择性，低的积炭量和较长的催化剂使用寿命。 研究了催化剂表面的疏水疏油性在醋酸与正丁醇的酯化反应中的应用。结果显示，当酯化反应产物为液相时，催化剂表面的疏水疏油性非常有利于产物从催化剂表面脱附，能有效提高正丁醇的转化率。 关键词：酸强度，钨硅酸，聚四氟乙烯，疏油性，寿命

气相贝克曼重排新型固体酸催化剂研究

己内酰胺是一种重要的有机化工原料。采用环己酮肟的气相Beckmann重排的方法制己内酰胺可以解决传统的液相工艺中存在的副产硫酸胺、腐蚀设备和污染环境等问题。本研究的目的是开发出适合环己酮肟的气相Beckmann重排的固体酸催化新工艺。 首先，本工作用同位素标记的方法研究了Beckmann重排在固体酸B2O3/γ-Al2O3和TS-1上的反应机理。同位素标记后的产品采用质谱测量。通过与H218O交换氧，发现环己酮肟与H218O的交换在B2O3/γ-Al2O3和TS-1只能进行到一定程度，这暗示固体酸上腈中间体的解离不如经典的机理完全。提出了解离度(α)的概念，其定义为解离了中间体腈与总中间体腈之比。通过拟合实验数据和同位素标记的产品的计算公式，获得了B2O3/γ-Al2O3和TS-1上α 值分别为0.199和0.806的结果。 其次，采用对氧化铝表面合适氟化的方法，对氟化的氧化铝的性能进行研究。发现氧化铝表面氟化可以改善Beckmann重排的性能。氧化铝表面氟化可以消除其表面碱性位，说明了催化剂表面碱性位不利于Beckmann重排。而完全氟化的氧化铝的选择性不如某些固体酸如负载B2O3和Silicalite-1，暗示着表面酸强度也影响催化剂的选择性。同时，我们对适合气相Beckmann重排的催化剂进行了简单的筛选。发现一种稀土焦磷酸盐有可能是适合此反应的催化剂。 再次，研究了稀土焦磷酸盐催化剂上气相Beckmann重排。通过对一些稀土磷酸进行XRD,FT-IR,NH3-TPD和水接触角等表征，发现这类催化剂上表面的弱酸位以及合适的表面疏水是它们具有较好性能的原因。 再次，对焦磷酸铈催化剂的合成以及反应氛围进行了优化。发现优化的反应氛围为催化剂在pH在3~4时沉淀，在500~550度焙烧，在~350度反应，载气~80ml/min，空速在0.43h-1时反应，能保持转化率在98％以上，选择性在70％以上，8小时不失活。 最后，采用P123作为模板剂合成了一种新型的中孔稀土磷酸盐，这种稀土磷酸盐具有无序的虫洞形结构。应用这种新型的中孔稀土磷酸盐于酚类甲醇氧烷基化获得了较好的结果。与不加表面活性剂的材料相比，这种中孔稀土磷酸盐在低温下具有更大的活性并且其选择性不受损失。认为这种中孔的形态对催化性能具有好的影响。