Generating assembled MFI nanocrystals with reduced b‐axis through structure‐directing agent exchange induced recrystallization

2021 ◽  
Author(s):  
Xiaoling Zhao ◽  
Shu Zeng ◽  
Xueliang Zhang ◽  
Quanzheng Deng ◽  
Xiujie Li ◽  
...  
Keyword(s):  
Structure Directing Agent

Positive Role of Synthesis Method and Hard Template on the Catalytic Performance of SAPO-34 in Methanol to Olefin Reaction.

2020 ◽  
Vol 23 ◽  
Author(s):  
Sajjad Rimaz ◽  
Reza Katal
Keyword(s):  
Particle Size ◽  
Synthesis Method ◽  
Catalytic Performance ◽  
Hard Template ◽  
Structure Directing Agent ◽  
Positive Role ◽  
Methanol To Olefin ◽  
Dg Method ◽  
Synthesis Procedure

: In the present study, SAPO-34 particles were synthesized using hydrothermal (HT) and dry gel (DG) conversion methods in the presence of diethyl amine (DEA) as an organic structure directing agent (SDA). Carbon nanotubes (CNT) were used as hard template in the synthesis procedure to introduce transport pores into the structures of the synthesized samples. The synthesized samples were characterized with different methods to reveal effects of synthesis method and using hard template on their structure and catalytic performance in methanol to olefin reaction (MTO). DG conversion method results in smaller particle size in comparison with hydrothermal method, resulting in enhancing catalytic performance. On the other side, using CNT in the synthesis procedure with DG method results in more reduction in particle size and formation of hierarchical structure which drastically improves catalytic performance.

Preparation of Organized Mesoporous Silica from Sodium Metasilicate Solutions in Alkaline Medium Using Nonionic Surfactants

2003 ◽  
Vol 68 (10) ◽  
pp. 2019-2031 ◽  
Author(s):  
Markéta Zukalová ◽  
Jiří Rathouský ◽  
Arnošt Zukal
Keyword(s):  
Mesoporous Silica ◽  
Ethylene Oxide ◽  
Sodium Metasilicate ◽  
Spherical Particles ◽  
Structure Directing Agent ◽  
Inorganic Species ◽  
Poly Ethylene Oxide ◽  
Acidic Conditions ◽  
Poly Ethylene ◽  
Hydrolysis Of

A new procedure has been developed, which is based on homogeneous precipitation of organized mesoporous silica from an aqueous solution of sodium metasilicate and a nonionic poly(ethylene oxide) surfactant serving as a structure-directing agent. The decrease in pH, which induces the polycondensation of silica, is achieved by hydrolysis of ethyl acetate. Owing to the complexation of Na+ cations by poly(ethylene oxide) segments, assembling of the mesostructure appears to occur under electrostatic control by the S0Na+I- pathway, where S0 and I- are surfactant and inorganic species, respectively. As the complexation of Na+ cations causes extended conformation of poly(ethylene oxide) segments, the pore size and pore volume of organized mesoporous silica increase in comparison with materials prepared under neutral or acidic conditions. The assembling of particles can be fully separated from their solidification, which results in the formation of highly regular spherical particles of mesoporous silica.

Structure-directing study of 1-methylimidazolium-based dication with tetramethylene as spacer length in the synthesis of microporous silicoaluminophosphates

2021 ◽  
Author(s):  
Thayara Kellen Tavares ◽  
Gabrielli Almeida ◽  
Yuri Variani ◽  
Katia Bernardo-Gusmão ◽  
Paloma Vinaches ◽  
...  
Keyword(s):  
Structure Directing Agent ◽  
Spacer Length ◽  
Organic Structure ◽  
Directing Effect

In this work we study the structure-directing effect of 1-methylimidazolium-based dications with four methylene units as spacer length (4BI), as Organic Structure-Directing Agent (OSDA) in the synthesis of silicoaluminophosphate (SAPO)...

scholarly journals Offretite Zeolite Single Crystals Synthesized by Amphiphile-Templating Approach

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2238
Author(s):  
Eng-Poh Ng ◽  
Nur Hidayahni Ahmad ◽  
Fitri Khoerunnisa ◽  
Svetlana Mintova ◽  
Tau Chuan Ling ◽  
...  
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Cost Effective ◽  
Acid Sites ◽  
Biofuel Production ◽  
Structure Directing Agent ◽  
High Crystallinity ◽  
Organic Templates ◽  
Synthesis Approach ◽  
Conventional Counterpart ◽  
Dual Functions

Offretite zeolite synthesis in the presence of cetyltrimethylammonium bromide (CTABr) is reported. The offretite crystals were synthesized with a high crystallinity and hexagonal prismatic shape after only 72 h of hydrothermal treatment at 180 °C. The CTABr has dual-functions during the crystallization of offretite, viz. as structure-directing agent and as mesoporogen. The resulting offretite crystals, with a Si/Al ratio of 4.1, possess more acid sites than the conventional offretite due to their high crystallinity and hierarchical structure. The synthesized offretite is also more reactive than its conventional counterpart in the acylation of 2-methylfuran for biofuel production under non-microwave instant heating condition, giving 83.5% conversion with 100% selectivity to the desired product 2-acetyl-5-methylfuran. Hence, this amphiphile synthesis approach offers another cost-effective and alternative route for crystallizing zeolite materials that require expensive organic templates.

scholarly journals AFX Zeolite for Use as a Support of NH3-SCR Catalyst Mining through AICE Joint Research Project of Industries–Academia–Academia

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 163
Author(s):  
Masaru Ogura ◽  
Yumiko Shimada ◽  
Takeshi Ohnishi ◽  
Naoto Nakazawa ◽  
Yoshihiro Kubota ◽  
...  
Keyword(s):  
High Performance ◽  
Ionic Species ◽  
Research Project ◽  
Joint Research ◽  
Structure Directing Agent ◽  
Scr Catalyst ◽  
Organic Structure ◽  
Nh3 Scr ◽  
Joint Research Project ◽  
The One

This paper introduces a joint industries–academia–academia research project started by researchers in several automobile companies and universities working on a single theme. Our first target was to find a zeolite for NH3-SCR, that is, zeolite mining. Zeolite AFX, having the same topology of SSZ-16, was found to be the one of the zeolites. SSZ-16 can be synthesized by using an organic structure-directing agent such as 1,1′-tetramethylenebis(1-azonia-4-azabicyclo[2.2.2]octane; Dab-4, resulting in the formation of Al-rich SSZ-16 with Si/Al below five. We found that AFX crystallized by use of N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium ion, called TEBOP in this study, had the same analog as SSZ-16 having Si/Al around six and a smaller particle size than SSZ-16. The AFX demonstrated a high performance for NH3-SCR as the zeolitic support to load a large number of divalent Cu ionic species with high hydrothermal stability.

scholarly journals Hierarchical Porous, N-Containing Carbon Supports for High Loading Sulfur Cathodes

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 408
Author(s):  
Jae-Woo Park ◽  
Hyun Jin Hwang ◽  
Hui-Ju Kang ◽  
Gazi A. K. M. Rafiqul Bari ◽  
Tae-Gyu Lee ◽  
...  
Keyword(s):  
High Energy ◽  
High Energy Density ◽  
High Loading ◽  
Carbon Supports ◽  
Structure Directing Agent ◽  
Shuttle Effect ◽  
Main Challenge ◽  
Hierarchical Porous ◽  
Hollow Carbon ◽  
A Minor

The lithium-polysulfide (LiPS) dissolution from the cathode to the organic electrolyte is the main challenge for high-energy-density lithium-sulfur batteries (LSBs). Herein, we present a multi-functional porous carbon, melamine cyanurate (MCA)-glucose-derived carbon (MGC), with superior porosity, electrical conductivity, and polysulfide affinity as an efficient sulfur support to mitigate the shuttle effect. MGC is prepared via a reactive templating approach, wherein the organic MCA crystals are utilized as the pore-/micro-structure-directing agent and nitrogen source. The homogeneous coating of spherical MCA crystal particles with glucose followed by carbonization at 600 °C leads to the formation of hierarchical porous hollow carbon spheres with abundant pyridinic N-functional groups without losing their microstructural ordering. Moreover, MGC enables facile penetration and intensive anchoring of LiPS, especially under high loading sulfur conditions. Consequently, the MGC cathode exhibited a high areal capacity of 5.79 mAh cm−2 at 1 mA cm−2 and high loading sulfur of 6.0 mg cm−2 with a minor capacity decay rate of 0.18% per cycle for 100 cycles.

scholarly journals Few‐unit‐cell MFI zeolite synthesized using a simple di‐quaternary ammonium structure‐directing agent

2021 ◽  
Author(s):  
Michael Tsapatsis ◽  
Peng Lu ◽  
Supriya Ghosh ◽  
Matheus Dorneles de Mello ◽  
Huda Sharbini Kamaluddin ◽  
...  
Keyword(s):  
Quaternary Ammonium ◽  
Unit Cell ◽  
Mfi Zeolite ◽  
Structure Directing Agent

scholarly journals Organic Structure-Directing Agent-Free Synthesis of Mordenite-Type Zeolites Driven by Al-Rich Amorphous Aluminosilicates

ACS Omega ◽  
2021 ◽  
Author(s):  
Ting Xiao ◽  
Mizuho Yabushita ◽  
Toshiki Nishitoba ◽  
Ryota Osuga ◽  
Motohiro Yoshida ◽  
...  
Keyword(s):  
Structure Directing Agent ◽  
Organic Structure

A powerful structure-directing agent for the synthesis of nanosized Al- and high-silica zeolite Beta in alkaline medium

2011 ◽  
Vol 142 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Olivier Larlus ◽  
Svetlana Mintova ◽  
Stephen T. Wilson ◽  
Richard R. Willis ◽  
Hayim Abrevaya ◽  
...  
Keyword(s):  
Alkaline Medium ◽  
Zeolite Beta ◽  
Structure Directing Agent ◽  
High Silica
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