9003-07-0Relevant articles and documents
Glycerol Isopropyl Ethers: Direct Synthesis from Alcohols and Synthesis by the Reduction of Solketal
Samoilov, Vadim O.,Onishchenko, Maria O.,Ramazanov, Dzhamalutdin N.,Maximov, Anton L.
, p. 2839 - 2849 (2017)
The catalytic reduction of solketal ((2,2-dimethyl-1,3-dioxolan-4-yl)methanol) over bifunctional heterogeneous palladium catalysts is proposed as an alternative to the synthesis of glycerol isopropyl ethers by the etherification of glycerol. The direct synthesis of glycerol isopropyl ethers from isopropanol and glycerol requires severe conditions (T=130–150 °C, p(H2)=20–35 bar) and a large excess of isopropanol to reach a considerable yield. The main reaction products in the catalytic reduction of solketal are glycerol mono- and di-isopropyl ethers and solketal isopropyl ether. Solketal conversion over Al-HMS-supported palladium catalysts (T=120 °C and p(H2)=20 bar) affords a mixture of ethers with a high degree of conversion (87 %), 78 % selectivity, and excellent regioselectivity between isomeric ethers. Zeolite-BEA-supported palladium catalysts also exhibit high activity but much lower selectivity because of intense acetone aldol condensation. The effects of Si/Al ratios in BEA zeolites and Al-HMS aluminosilicates and the amounts of supported palladium (1 and 2 wt %) on the properties of the catalysts at different reaction temperatures and hydrogen pressures are considered.
A pronounce approach on the catalytic performance of mesoporous natural silica toward esterification of acetic acid with iso-amyl, benzyl, and cinnamyl alcohols
Said, Abd El-Aziz A.,Abd El-Wahab, Mohamed M. M.,El-Gamal, Nadia O.,Goda, Mohamed N.
, p. 257 - 268 (2021/12/14)
Catalytic esterification of acetic acid with iso-amyl, benzyl, and cinnamyl alcohols in the liquid phase over unmodified natural silica catalyst has been studied. The virgin and calcined catalysts were characterized by thermal analyses (Thermogravimetry (TG) and diffrential thermal analysis (DTA)), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and N2 sorption analyses. The acidity of natural silica catalysts was investigated using isopropyl alcohol dehydration and chemisorption of pyridine and dimethyl pyridine. The results indicated that most of the acidic sites are of Br?nsted type and of intermediate strength. The effect of different parameters such as reaction time, molar ratio, catalyst dosage, and calcination temperature was studied. Natural silica catalyst exhibited excellent catalytic performance with a selectivity of 100% to acetate esters formation. The maximum yields of isoamyl, benzyl, and cinnamyl acetate esters obtained in the batch conditions were 80, 81, and 83%, respectively. Whereas on adopting a simple distillation technique, these yields were successfully improved to higher values of 97, 98, and 90%, respectively. Experimental results manifested that the reaction followed Langmuir–Hinshelwood mechanism. Finally, the catalyst could be completely recycled without loss of its activity after four cycles of the esterification reactions.
A ZEOLITE CATALYST AND USE THEREOF FOR THE DEHYDROGENATION OF ALKANES
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Page/Page column 29-31, (2022/02/05)
The present invention relates to a zeolite catalyst, wherein the zeolite catalyst comprises a zeolitic material, wherein the framework of the zeolitic material comprises Y02 and X203, wherein Y is a tetravalent element and X is a trivalent element, wherein the Y : X molar ratio of Y and X contained in the framework of the zeolitic material is comprised in the range of from 500 to 10,000, and wherein the zeolite catalyst further comprises Pt which is supported on the zeolitic material. Furthermore, the present invention relates to a molding comprising the zeolite catalyst, as well as to processes for the preparation of the molding. The present invention also relates to a process for the dehydrogenation of alkanes using the inventive zeolite catalyst or molding, as well as to their respective use. In particular, the catalyst can be Pt/ZSM-5, Pt-Zn/ZSM-5, Pt-K/ZSM-5 or Pt-Zn-K / ZSM-5, with the zeolite exhibiting a Si/A I molar ratio of 850.
Investigation on the Thermal Cracking and Interaction of Binary Mixture of N-Decane and Cyclohexane
Chen, Xuejiao,Pang, Weiqiang,Wang, Bo,Zhang, Ziduan,Zhou, Lingxiao,Zhu, Quan
, (2022/03/02)
Abstract: The investigation about the thermal cracking performance and interaction of different components in hydrocarbon fuels is of great significance for optimizing the formulation of high-performance hydrocarbon fuels. In this work, thermal cracking of n-decane, cyclohexane and their binary mixture were studied in a tubular reactor under different temperatures and pressures. The gas and liquid products were analyzed in detail with different gas chromatography. The main gas products of pure n-decane and cyclohexane are similar, and there is a certain difference in the main liquid products. For binary mixture, the overall conversion rate and gas yield are lower than their theoretical value. The cracking conversion rate of n-decane in binary mixture is lower than that in pure n-decane, but the opposite change occurs for cyclohexane, and the effect become more obvious as the increase of the reaction pressure. These experimental phenomena can be explained by bond dissociation energy and free radical reaction mechanism. The pressure affects the free radical reaction path, and high pressure is more conducive to bimolecular hydrogen abstraction reaction, which will lead to different product content. A law of interaction between the n-decane and cyclohexane was observed according to the experimental results. [Figure not available: see fulltext.]
Impact of composition and structural parameters on the catalytic activity of MFI type titanosilicalites
Bruk, Lev,Chernyshev, Vladimir,Khramov, Evgeny,Kravchenko, Galina,Kustov, Aleksander,Kustov, Leonid,Kuz'Micheva, Galina,Markova, Ekaterina,Pastukhova, Zhanna,Pirutko, Larisa
, p. 3439 - 3451 (2022/03/14)
Titanosilicalite of the MFI type was obtained via a hydrothermal method. Its initial and annealed at 75 °C (TS-1P(75)) and 500 °C (TS-1P(500)) forms were studied by X-ray powder diffraction (PXRD), X-ray absorption spectroscopy (XAS-method), Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), temperature-programmed ammonia desorption (TPD NH3), and pyridine adsorption (Py). The full-profile Rietveld method allowed us to observe the presence of the organic template tetrapropylammonium hydroxide (TPAOH) in the framework voids, as well as to determine the silicate module (Si/Ti = 73.5) and the distribution of Ti4+ ions over the MFI-type structure sites (Ti atoms replace Si ones in two positions: T1 and T6). The coordination numbers of titanium (CNTi = 4.6 for TS-1P and TS-1P(75), CNTi = 3.8 for TS-1P(500)) were established by the XAS-method. The catalytic activity of titanosilicalites was found in the reactions of nitrous oxide decomposition (the maximal decomposition rate is demonstrated for the TS-1P(75) sample), allyl chloride epoxidation to epichlorohydrin (the best combination of all indicators was exhibited for the TS-1P sample) and propane conversion (maximum propane conversion, and butadiene and propylene selectivity were observed in both TS-1P(75) and TS-1P(500) samples). Mechanisms for the catalytic processes are proposed. The relationship between the catalytic properties and the composition (Si/Ti), Ti4+ ion distribution over the MFI-type structure sites, the local environment of titanium ions, and the number of acid sites in the titanosilicalites are discussed.
TfO-···H-O-H Interaction-Assisted Generation of a Silicon Cation from Allylsilanes: Access to Phenylallyl Ferrier Glycosides from Glycals
Addanki, Rupa Bai,Halder, Suvendu,Kancharla, Pavan K.
supporting information, p. 1465 - 1470 (2022/02/23)
We demonstrate here that the strained and bulky protonated 2,4,6-tri-tert-butylpyridine (TTBPy) triflate salt serves as a mild and efficient organocatalyst for the diastereoselective C-Ferrier glycosylation of various glycals. The importance of the role of the 1/2 H2O molecule trapped in the catalyst has been disclosed. The mechanism of action involves unique anionic triflate and H2O hydrogen-bond interactions that assist the activation of allylsilanes, providing unprecedented access to diastereoselective phenylallyl Ferrier glycosides.
Alcohol-assisted synthesis of high-silica zeolites in the absence of organic structure-directing agents
Luan, Huimin,Lei, Chi,Ma, Ye,Wu, Qinming,Zhu, Longfeng,Xu, Hao,Han, Shichao,Zhu, Qiuyan,Liu, Xiaolong,Meng, Xiangju,Xiao, Feng-Shou
, p. 563 - 570 (2020/09/01)
In this work, we show for the first time that high-silica zeolites (MFI, TON, MTT, and *MRE) could be synthesized from a combined strategy of both zeolite seeding and alcohol filling in the absence of organic structure-directing agents (OSDAs). High-silica ZSM-5 zeolites with Si/Al ratios ranging from 38 to 240 (TF-Al-ZSM-5) could be synthesized via this route. The key to the success of this technique was the employment of an aluminosilicate precursor with a fully 4-coordinated aluminum species as the initial source, wherein the rearrangement and condensation of the silicate species, rather than the aluminate species, occurred during zeolite crystallization. In addition, heteroatoms, such as Fe and B, could be incorporated into the zeolite frameworks. Catalytic tests for the methanol-to-propylene (MTP) reaction exhibited good catalytic performance for TF-Al-ZSM-5, which was comparable to that of the aluminosilicate ZSM-5 zeolite synthesized with OSDAs. Hence, this method offers viable opportunities for the industrial production and catalytic application of high-silica zeolites in the future.
Transformation synthesis of SSZ-13 zeolite from ZSM-35 zeolite
Bing, Liancheng,Cong, Wenwen,Han, Dezhi,Li, Kexu,Li, Qiang,Wang, Fang,Wang, Guangjian,Xu, Changyou
, (2021/10/06)
Interzeolite conversion as a promising alternative strategy for zeolite synthesis has received extensive attention. It is of great significance to understand the potential rules of conversion between zeolites with different topologies for effective regulation of zeolite synthesis. Hydrothermal conversion of ZSM-35 (FER-type) zeolite containing the mor composite building units into SSZ-13 zeolite (CHA-type) using N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) as template was performed for the first time. The effects of TMAdaOH/SiO2 ratio, Na2O/SiO2 ratio, the additional starting zeolite and crystallization time on the interzeolite conversion of ZSM-35 into SSZ-13 were investigated. The interzeolite conversion mechanism concerning the synthesis of SSZ-13 from ZSM-35 zeolite was proposed and verified by DFT calculation. The results of DFT calculations suggested that ZSM-35 zeolite with mor composite building unit had the potential to decompose into 6-Membered Rings, and further transform into CHA-type zeolite containing d6r composite building unit. Therefore, zeolites containing mor structure have the potential to be converted into zeolites containing d6r structure.
CATALYST AND METHOD FOR PREPARING LIGHT OLEFIN USING DIRECT CONVERSION OF SYNGAS
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Paragraph 0082; 0085, (2021/04/30)
A catalyst for preparing light olefin using direct conversion of syngas is a composite catalyst and formed by compounding component I and component II in a mechanical mixing mode. The active ingredient of component I is a metal oxide; and the component II is one or more than one of zeolite of CHA and AEI structures or metal modified CHA and/or AEI zeolite. A weight ratio of the active ingredients in the component Ito the component II is 0.1-20. The reaction process has high product yield and selectivity, wherein the sum of the selectivity of the propylene and butylene reaches 40-75%; and the sum of the selectivity of light olefin comprising ethylene, propylene and butylene can reach 50-90%. Meanwhile, the selectivity of a methane side product is less than 15%.
Bridging the Gap: From Homogeneous to Heterogeneous Parahydrogen-induced Hyperpolarization and Beyond
Chekmenev, Eduard Y.,Goodson, Boyd M.,Bukhtiyarov, Valerii I.,Koptyug, Igor V.
, p. 710 - 715 (2021/04/14)
Demonstration of parahydrogen-induced polarization effects in hydrogenations catalyzed by heterogeneous catalysts instead of metal complexes in a homogeneous solution has opened an entirely new dimension for parahydrogen-based research, demonstrating its applicability not only for the production of catalyst-free hyperpolarized liquids and gases and long-lived non-equilibrium spin states for potential biomedical applications, but also for addressing challenges of modern fundamental and industrial catalysis including advanced mechanistic studies of catalytic reactions and operando NMR and MRI of reactors. This essay summarizes the progress achieved in this field by highlighting the research contributed to it by our colleague and friend Kirill V. Kovtunov whose scientific career ended unexpectedly and tragically at the age of 37. His role in this research was certainly crucial, further enhanced by a vast network of his contacts and collaborations at the national and international level.
