Read by QxMD icon Read


Claudia Belviso
The action of direct sonication (US) versus conventional hydrothermal method (HY) was investigated to determine the differences in the crystallization mechanism of zeolite formed from fly ash. The results showed that ultrasonic energy is decisive in very fast faujasite and A-type zeolite transformation into more stable sodalite phase. The data display the main presence of sodalite together with a low amount of faujasite and zeolite A after the first 3 h of sonication. The full transformation of the latter two phases into sodalite takes place after 1 h more of treatment...
May 2018: Ultrasonics Sonochemistry
Shirin Heidari, Mohammad Haghighi, Maryam Shabani
Bi2 Sn2 O7 -C3 N4 /Y nanophotocatalyst with various ratios of zeolite and high activity under simulated solar light irradiation were successfully synthesized using ultrasound-assisted dispersion method. The effect of different amounts of zeolite (10, 20 and 30 wt%) on the photocatalytic degradation of antibiotic tetracycline was investigated. The as-prepared nanophotocatalysts were characterized by XRD, FESEM, EDX, BET, FTIR, DRS and pHpzc techniques. The degradation results demonstrated that, Bi2 Sn2 O7 -C3 N4 /Y(10) nanophotocatalyst with a degradation efficiency of about 80...
May 2018: Ultrasonics Sonochemistry
Xiaohua Li, Xiaolei Zhang, Shanshan Shao, Liangxiu Dong, Jin Zhang, Chao Hu, Yixi Cai
Catalytic upgrading of pyrolysis vapor from rape straw was performed in a vacuum pyrolysis system over La/HZSM-5 with hierarchical structure. When 3M Na2 CO3 was used for alkali treatment, the desilication process of HZSM-5 zeolite was highly controllable and the hierarchical porous HZSM-5(Hi-ZSM-5) zeolite was formed. After that, Hi-ZSM-5 was modified by impregnation with lanthanum ion, the acid sites of Lewis increased and the concentrations ratio of Brönsted acid and Lewis acid of the catalyst was improved...
March 14, 2018: Bioresource Technology
Shaobo Li, Madushani Dharmarwardana, Raymond P Welch, Candace E Benjamin, Alexandra Shamir, Steven O Nielsen, Jeremiah J Gassensmith
Biomimetic mineralization with metal-organic frameworks (MOF), typically zeolitic imidazolate framework-8 (ZIF-8), is an emerging strategy to protect sensitive biological substances against denaturing environmental stressors like heat and proteolytic agents. Additionally, this same biomimetic mineralization process has the potential of being used to create distinct core-shell architectures using genetically or chemically modified viral nanoparticles. Despite the proliferation of examples for ZIF-8 growth on biological or proteinaceous substrates, systematic studies of these processes are few and far between...
March 19, 2018: ACS Applied Materials & Interfaces
Lovjeet Singh, Pawan Rekha, Shri Chand
In order to find a better alternative of conventional aqueous ion-exchange method, several Cu/zeolite Y samples were synthesized by different routes and examined for the catalytic wet peroxide oxidation of quinoline aqueous solution in continuous fixed-bed reactor. The characterization of catalysts using ICPMS, XRD, N2 sorption, UV-vis DRS, FESEM and XPS techniques reveals the profound influence of preparation methods on synergy between copper-support interfaces. Aqueous ion-exchange (CuYAIE ) and wet-impregnation (CuYIMP ) methods promoted isolated Cu1+/2+ species; however, large crystallites of CuO were present on the external surface of precipitation-impregnation (CuYPI ) catalyst...
March 15, 2018: Journal of Environmental Management
Carolina Petitto, Gérard Delahay
Nitrogen oxides (NOx : NO, NO2 ) are a concern due to their adverse health effects. Diesel engine transport sector is the major emitter of NOx . The regulations have been strengthened and to comply with them, one of the two methods commonly used is the selective catalytic reduction of NOx by NH3 (NH3 -SCR), NH3 being supplied by the in-situ hydrolysis of urea. Efficiency and durability of the catalyst for this process are highly required. Durability is evaluated by hydrothermal treatment of the catalysts at temperature above 800°C...
March 2018: Journal of Environmental Sciences (China)
Seungtaik Hwang, Arun Gopalan, Maximilian Hovestadt, Frank Piepenbreier, Christian Chmelik, Martin Hartmann, Randall Q Snurr, Jörg Kärger
Molecular diffusion is commonly found to slow down with increasing molecular size. Deviations from this pattern occur in some host materials with pore sizes approaching the diameters of the guest molecules. A variety of theoretical models have been suggested to explain deviations from this pattern, but robust experimental data are scarcely available. Here, we present such data, obtained by monitoring the chain length dependence of the uptake of n- alkanes in the zeolitic imidazolate framework ZIF-4. A monotonic decrease in diffusivity from ethane to n- butane was observed, followed by an increase for n- pentane, and another decrease for n- hexane...
March 15, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
S Thiyagarajan, V Edwin Geo, Leenus Jesu Martin, B Nagalingam
This experimental study aims to mitigate harmful emissions from a CI engine using bio-energy with carbon capture and storage (BECCS) approach. The engine used for this experimental work is a single cylinder CI engine with a rated power of 5.2 kW at a constant speed of 1500 rpm. The BECCS approach is a combination of plant-based biofuels and carbon capture and storage system. The whole investigation was done in four phases: (1) Substituting diesel with Karanja oil methyl ester (KOME) (2) Equal volume blending of Orange oil (ORG) with KOME (3) 20% blending of n-butanol (B) with KOME-ORG blend (4) Carbon capture and storage (CCS) system with zeolite based non-selective catalytic reduction (NSCR) and mono ethanolamine (MEA) based selective non-catalytic reduction (SNCR) system with KOME-ORG + B20 blend...
March 15, 2018: Environmental Technology
Ya Guo, Tianjun Sun, Yiming Gu, Xiaowei Liu, Quanli Ke, Shudong Wang
Zeolite FAU with tunable SiO₂/Al₂O₃ molar ratio has been successfully synthesized in the absence of organic structure-directing agents (OSDA). Specifically, the addition of zinc species contributes to the feasible and effective adjustment of the framework SiO₂/Al₂O₃ molar ratio between ca. 4 and ca. 6 depending on the amount of zinc species added in the batch composition. In contrast, typical OSDA such as tetramethylammonium hydroxide (TMAOH) has a limited effect on the SiO₂/Al₂O₃ molar ratio of the zeolite...
March 15, 2018: Chemistry, An Asian Journal
Liancheng Bing, Aixiu Tian, Fang Wang, Kaifeng Yi, Xingyuan Sun, Guangjian Wang
Hierarchical SSZ-13 microspheres with abundant mesoporous channels have been successfully synthesized by addition of calcined SSZ-13 crystals in the starting gel in the absence of any organic templates. This strategy not only remarkably reduces the production cost and environmental pollution but also significantly decreases the crystallization time as well as evidently reducing the zeolite crystal sizes in many cases. The synthesized sample was characterized by XRD, BET, ICP, SEM, TEM, TG, and NH3-TPD, which indicates that the organic template free synthesized SSZ-13 exhibits high crystallinity, textural properties, and acidity...
March 15, 2018: Chemistry: a European Journal
Lars Borchardt, Mirian Elizabeth Casco, Joaquin Silvestre-Albero
Methane hydrate inheres the great potential to be a nature-inspired alternative for chemical energy storage, since it allows to store large amounts of methane in a dense solid phase. The embedment of methane hydrate in the confined environment of porous materials can be capitalized for potential applications as its physico-chemical properties such as the formation kinetics or pressure and temperature stability are significantly changed as compared to the bulk system. We review this topic from a materials scientific perspective by considering porous carbons, silica, clays, zeolites, and polymers as host structure for methane hydrate formation...
March 14, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Guoxiong Wang, Shaodan Xu, Liang Wang, Zhiqiang Liu, Xue Dong, Lingxiang Wang, Anmin Zheng, Xiangju Meng, Feng-Shou Xiao
A fish-in-hole strategy for preparing a Pd nanoparticle catalyst was reported, which is achieved by controllable positioning of Pd nanoparticles individually at the traps of zeolite crystals. This Pd catalyst was sinter-resistant under high-temperature calcination and CO oxidation, outperforming the conventional supported catalyst consisting of supported Pd nanoparticles synthesized via the traditional deposition method.
March 14, 2018: Chemical Communications: Chem Comm
Ang Qiao, Thomas D Bennett, Haizheng Tao, Andraž Krajnc, Gregor Mali, Cara M Doherty, Aaron W Thornton, John C Mauro, G Neville Greaves, Yuanzheng Yue
Glass-forming ability (GFA) is the ability of a liquid to avoid crystallization during cooling. Metal-organic frameworks (MOFs) are a new class of glass formers ( 1 - 3 ), with hitherto unknown dynamic and thermodynamic properties. We report the discovery of a new series of tetrahedral glass systems, zeolitic imidazolate framework-62 (ZIF-62) [Zn(Im2- x bIm x )], which have ultrahigh GFA, superior to any other known glass formers. This ultrahigh GFA is evidenced by a high viscosity η (105 Pa·s) at the melting temperature T m , a large crystal-glass network density deficit (Δρ/ρg )network , no crystallization in supercooled region on laboratory time scales, a low fragility ( m = 23), an extremely high Poisson's ratio (ν = 0...
March 2018: Science Advances
Roberto Christian Arbulu, Ying-Bing Jiang, Eric John Peterson, Yang Qin
New mechanisms of controlled growth of one-dimensional (1D) metal-organic framework (MOF) nano- and super-structures under size-confinement and surface directing effects have been discovered. Through applying interfacial synthesis templated by track-etched polycarbonate (PCTE) membranes, congruent polycrystalline zeolitic imidazolate framework-8 (ZIF-8) solid nanorods and hollow nanotubes were found to form within 100 nm membrane pores, while single crystalline ZIF-8 nanowires grew inside 30 nm pores, all of which possess large aspect ratios up to 60 and show preferential crystal orientation with the {100} planes aligned parallel to the pore's long axis...
March 13, 2018: Angewandte Chemie
Taro Shimonosono, Yoshihiro Hirata, Kyohei Nishikawa, Soichiro Sameshima, Kenichi Sodeyama, Takuro Masunaga, Yukio Yoshimura
A zeolite (mordenite)-pore-phenol resin composite and a zeolite-pore-shirasu glass composite were fabricated by hot-pressing. Their thermal conductivities were measured by a laser flash method to determine the thermal conductivity of the monolithic zeolite with the proposed mixing rule. The analysis using composites is useful for a zeolite powder with no sinterability to clarify its thermal properties. At a low porosity <20%, the thermal conductivity of the composite was in excellent agreement with the calculated value for the structure with phenol resin or shirasu glass continuous phase...
March 13, 2018: Materials
Chuanqi Zhang, Elina Kapaca, Jiyang Li, Yunling Liu, Xianfeng Yi, Anmin Zheng, Xiaodong Zou, Jiuxing Jiang, Jihong Yu
Extra-large pore zeolites have aroused increasing interests because of their important applications for possessing of large molecules. Although great progress has been made by academy and industry, it is challenging to synthesize these materials. A new extra-large pore zeolite SYSU-3 (Sun Yat-sen University no. 3) has been synthesized by using a novel sophoridine derivative as an organic structure directing agent (OSDA). The framework structure was solved and refined using continuous rotation electron diffraction (cRED) data from nanosized crystals...
March 12, 2018: Angewandte Chemie
Matthew Witman, Sanliang Ling, Peter Boyd, Senja Barthel, Maciej Haranczyk, Ben Slater, Berend Smit
Scientific interest in two-dimensional (2D) materials, ranging from graphene and other single layer materials to atomically thin crystals, is quickly increasing for a large variety of technological applications. While in silico design approaches have made a large impact in the study of 3D crystals, algorithms designed to discover atomically thin 2D materials from their parent 3D materials are by comparison more sparse. We hypothesize that determining how to cut a 3D material in half (i.e., which Miller surface is formed) by severing a minimal number of bonds or a minimal amount of total bond energy per unit area can yield insight into preferred crystal faces...
February 28, 2018: ACS Central Science
Takayuki Iida, Koji Ohara, Yuriy Román-Leshkov, Toru Wakihara
Zeolites containing framework heteroatoms (e.g., Ti, Sn, and Hf) with open coordination sites behave as solid-state Lewis acids and exhibit remarkable catalytic properties unachievable with bulk oxides. However, direct evidence confirming the incorporation of such heteroatom species into the zeolite framework is difficult to obtain because of the limited number of analytical methods capable of discerning framework incorporation from extraframework species. In this work, the structural environments of hafnium (Hf) framework and extraframework species added post-synthetically into *BEA zeolites were analyzed using coupled pair distribution function (PDF) and diffuse reflectance (DR) UV-vis measurements...
March 12, 2018: Physical Chemistry Chemical Physics: PCCP
Xu Li, Jianwen Jiang
We report a density functional theory (DFT) study to investigate methanol-to-olefin (MTO) conversion in four types of ABC-6 zeolite cavities (cha, avl, aft and h1) by varying their shape and size. Based on a side-chain alkylation mechanism, the reaction energies and barriers of methylations, deprotonations and eliminations for hydrocarbon pool (HP) intermediates are calculated. In the cha cavity, methylations and eliminations are found to possess low barriers as attributed to the strong confinement effect of the elliptical and small cha cavity...
March 12, 2018: Physical Chemistry Chemical Physics: PCCP
Tao Du, Xin Fang, Liying Liu, Jin Shang, Bin Zhang, Yichao Wei, He Gong, Shamsur Rahman, Eric F May, Paul A Webley, Gang Kevin Li
High purity molecular trapdoor chabazite with an optimal Si/Al ratio (1:9) was prepared from fly ash. Gas adsorption isotherms and binary breakthrough experiments show dramatically large selectivities for CO2 over N2 and CH4 , which are the highest among physisorbents at operating temperatures suitable for postcombustion carbon capture and natural gas separations.
March 12, 2018: Chemical Communications: Chem Comm
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"