scholarly journals Improving the catalytic performance of SAPO-18 for the methanol-to-olefins (MTO) reaction by controlling the Si distribution and crystal size

2016 ◽  
Vol 6 (8) ◽  
pp. 2796-2806 ◽  
Author(s):  
Raquel Martínez-Franco ◽  
Zhibin Li ◽  
Joaquín Martínez-Triguero ◽  
Manuel Moliner ◽  
Avelino Corma
Keyword(s):  
Crystal Size ◽  
Organic Molecules ◽  
Chemical Properties ◽  
Catalytic Performance ◽  
Organic Structure ◽  
Mto Reaction ◽  
Physico Chemical ◽  
Small Pore ◽  
Structure Directing Agents

The physico-chemical properties of the small pore SAPO-18 zeotype have been controlled by properly selecting the organic molecules acting as organic structure directing agents (OSDAs).

scholarly journals A Multi-Nuclear MAS-NMR Study on the Structural Properties of Silicalite-1 Zeolite Synthesized Using N- and P-Based Organic Structure Directing Agents

2021 ◽  
Vol 11 (15) ◽  
pp. 6850
Author(s):  
Joaquin Martinez-Ortigosa ◽  
Jorge Simancas ◽  
Jose A. Vidal-Moya ◽  
Fernando Rey ◽  
Susana Valencia ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Structural Defects ◽  
Mfi Zeolite ◽  
Organic Structure ◽  
Pure Silica ◽  
Nmr Study ◽  
Physico Chemical ◽  
Structure Directing Agents ◽  
Nmr Methods ◽  
Charge Balancing

The nature of organic structure directing agents (OSDAs) is of paramount importance in the final properties of zeolites, particularly the framework and porosity. Recently, the use of P-containing OSDAs has been employed for new zeolites, but there is little discussion compared to their analogues N-OSDAs. The main objective of this work is the characterization of pure silica MFI zeolite (silicalite-1) prepared by the dual-template route with tetrapropylammonium (TPA), tetrapropylphosphonium (TPP) cations, and mixtures thereof aiming to understand by advanced NMR methods how the nature of the organic influences the physico-chemical properties of the zeolite. Silicalite-1 has been successfully synthesized using the dual-template procedure with TPA and TPP molecules. Both OSDAs are incorporated into the zeolite without any specific preference, differently to that observed before for the TEA/TEP system, and homogenously mixed inside of the zeolite voids. The presence of TPP leads to the incorporation of less F, raising the concentration of Q3-defective sites in the silicalite-1 zeolites. Detailed NMR results indicate that those structural defects are close to the –CH3 group of the entrapped OSDAs in the zeolite and these defects consist of at least two silanol groups stabilizing the Si-O- species, which is responsible for the charge balancing.

Fischer–Tropsch synthesis over the Fe–Mn/Al2O3 catalyst: modeling and optimization of light olefins using the RSM method

2020 ◽  
Vol 44 (42) ◽  
pp. 18457-18468
Author(s):  
Maryam Arsalanfar
Keyword(s):  
Chemical Properties ◽  
Catalytic Performance ◽  
Tropsch Synthesis ◽  
Light Olefins ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Modeling And Optimization ◽  
Physico Chemical ◽  
Al2o3 Catalyst

The effect of various preparation parameters on the catalytic performance and physico-chemical properties of a supported Fe–Mn catalyst was investigated using the RSM method.

scholarly journals Cage-based small-pore catalysts for NH3-SCR prepared by combining bulky organic structure directing agents with modified zeolites as reagents

2017 ◽  
Vol 217 ◽  
pp. 125-136 ◽  
Author(s):  
Nuria Martín ◽  
Cecilia Paris ◽  
Peter N.R. Vennestrøm ◽  
Joakim R. Thøgersen ◽  
Manuel Moliner ◽  
...  
Keyword(s):  
Organic Structure ◽  
Nh3 Scr ◽  
Small Pore ◽  
Modified Zeolites ◽  
Structure Directing Agents

Effect of Crystal Size on Physico-Chemical Properties of ZSM-5

2007 ◽  
Vol 120 (3-4) ◽  
pp. 288-293 ◽  
Author(s):  
Madhulika Singh ◽  
Raviraj Kamble ◽  
Nagabhatla Viswanadham
Keyword(s):  
Crystal Size ◽  
Chemical Properties ◽  
Physico Chemical

Synthesis of the Small Pore Silicoaluminophosphate STA-6 by Using Supramolecular Self-Assembled Organic Structure Directing Agents

2014 ◽  
Vol 26 (15) ◽  
pp. 4346-4353 ◽  
Author(s):  
Raquel Martínez-Franco ◽  
Ángel Cantín ◽  
Manuel Moliner ◽  
Avelino Corma
Keyword(s):  
Organic Structure ◽  
Small Pore ◽  
Structure Directing Agents ◽  
Self Assembled

Methanol Conversion on SAPO-34 Catalysts Synthesized by Tri-templates

2010 ◽  
Vol 1279 ◽  
Author(s):  
Liping Ye ◽  
Fahai Cao ◽  
Weiyong Ying ◽  
Dingye Fang ◽  
Qiwen Sun
Keyword(s):  
Surface Area ◽  
Crystal Size ◽  
Ammonium Hydroxide ◽  
Methanol Conversion ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
High Crystallinity ◽  
Templating Agent ◽  
Mto Reaction ◽  
Small Crystal Size

AbstractThe effect of different combinations of a new tri-templating agent TEAOH/DEA/TEA, namely tetraethyl ammonium hydroxide (TEAOH)/diethylamine (DEA)/triethylamine (TEA), on the catalytic performance of SAPO-34 was investigated in MTO conversion. It was found that SAPO-34 and SAPO-5 are competing phases at TEA concentrations higher than 40 %. Pure SAPO-34 with high crystallinity, large BET surface area and small crystal size (0.8~1.4μm) was obtained at a low TEA concentrations. The combination of TEAOH/DEA/TEA strongly governed the acidity of crystals. TEAOH:DEA:TEA=0.67:0.67:0.67 gave an economical catalyst active in MTO reaction with 100 % methanol conversion, 89.39 % ethylene and propylene selectivity, a longest lifetime and a high coke capability of 24.2 wt %.

scholarly journals Co-Adjuvant Nanoparticles for Radiotherapy Treatments of Oncological Diseases

2021 ◽  
Vol 11 (15) ◽  
pp. 7073
Author(s):  
Roberta Crapanzano ◽  
Valeria Secchi ◽  
Irene Villa
Keyword(s):  
Ionizing Radiation ◽  
Organic Molecules ◽  
Chemical Properties ◽  
Hybrid Nanoparticles ◽  
Oxygen Species ◽  
X Rays ◽  
X Ray ◽  
Power Amplification ◽  
Physico Chemical ◽  
Oncological Diseases

Nanomedicine is emerging as promising approach for the implementation of oncological methods. In this review, we describe the most recent methods exploiting heavy nanoparticles and hybrid nanomaterials aiming at improving the traditional X-rays-based treatments. High-Z nanoparticles are proposed as radiosensitizers due to their ability to stop the ionizing radiation and to increase the locally delivered therapeutic dose. Other nanoparticles working as catalysts can generate reactive oxygen species upon X-rays exposure. Thanks to their high toxicity and reactivity, these species promote DNA cancer cells damage and apoptosis. Hybrid nanoparticles, composed by scintillators coupled to organic molecules, are suitable in X-rays activated photodynamic therapy. This work highlights the roles played by the diverse nanoparticles, upon ionizing radiation irradiation, according to their physico-chemical properties, surface functionalization, and targeting strategies. The description of nanoparticle qualities demanded by the oncological nanomedicine is presented in relation to the processes occurring in biological medium when X-ray radiation interacts with heavy nanoparticles, including the scintillation mechanisms, the stopping power amplification, and the disputed modeling of the effective deposit of energy within nanomaterials. The comprehension of these issues in nanomedicine drives the strategies of nanoparticles engineering and paves the way for the development of advanced medical therapies.

scholarly journals Characteristics and activity of Ni/CeO2 catalyst modified by Cr2O3 in combined steam and CO2 reforming of CH4

2021 ◽  
Vol 10 (1) ◽  
pp. 104-108
Author(s):  
Phuong Phan Hong ◽  
Anh Nguyen Phung ◽  
Huy Tran Anh ◽  
Tri Nguyen ◽  
Loc Luu Cam
Keyword(s):  
Chemical Properties ◽  
Catalytic Performance ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Co2 Reforming ◽  
X Ray ◽  
Co2 Reforming Of Ch4 ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Temperature Programmed

A series of 10%wtNiO/CeO2-nanorod catalyst without and with Cr2O3 additive was prepared by simultaneous impregnation method. Several techniques, including N2 physisorption measurements, X-ray powder diffraction (XRD), temperature-programmed reduction using H2 (H2-TPR), CO2 temperature-programmed desorption (CO2-TPD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to investigate catalysts’ physico-chemical properties. The activity of the catalysts in combined steam and CO2 reforming of CH4 (BRM) was investigated at temperature range of 550-800 °C. The results showed that 10%NiO0.1%Cr2O3/CeO2 catalyst had the best catalytic performance due to a better reducibility and basicity. At 700 °C and CH4:CO2:H2O molar ratio in feed stream of 3:1.2:2.4, both conversion of CH4 and CO2 on this catalyst reached 98.5%.

scholarly journals Choosing the exponent in the definition of the connectivity index

2001 ◽  
Vol 66 (9) ◽  
pp. 605-611 ◽  
Author(s):  
Ivan Gutman ◽  
Mirko Lepovic
Keyword(s):  
Carbon Atom ◽  
Topological Index ◽  
Organic Molecules ◽  
Molecular Graph ◽  
Chemical Properties ◽  
Connectivity Index ◽  
Physico Chemical ◽  
Definition Of ◽  
Molecular Branching ◽  
Suitable Measure

Let ?v denote the degree of the vertex v of a molecular graph G. Then the connectivity index of G is defined as C (?) = G (?,C) = ? (?u?v)?, where the summation goes over all pairs of adjacent vertices. The exponent ? is usually chosen to be equal to -1/2, but other options were considered as well, especially ?=-1. We show that whereas C(-1/2) is a suitable measure of branching of the carbon-atom skeleton of organic molecules, and thus applicable as a topological index for modeling physico-chemical properties of the respective compounds, this is not the case with C(-1). The value of ? is established, beyond which C(?) fails to correctly reflect molecular branching.

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