scholarly journals TiCl4/MgCl2/MCM-41 Bi-Supported Ziegler–Natta Catalyst: Effects of Catalyst Composition on Ethylene/1-Hexene Copolymerization

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1535
Author(s):  
Xiaoyu Liu ◽  
Wenqi Guo ◽  
Xueer Wang ◽  
Yintian Guo ◽  
Biao Zhang ◽  
...  
Keyword(s):  
Active Center ◽  
Supported Catalysts ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Activation Effect ◽  
Catalyst Composition ◽  
Adsorption Analysis ◽  
Natta Catalyst ◽  
Polymerization Conditions ◽  
Mcm 41

TiCl4/MgCl2/MCM-41 type bi-supported Ziegler-Natta catalysts with different MgCl2/MCM-41 ratios were synthesized by adsorbing TiCl4 onto MgCl2 crystallites anchored in mesopores of MCM-41 (mesoporous silica with 3.4 nm pore size). Ethylene/1-hexene copolymerization with the catalysts was conducted at different 1-hexene concentrations and ethylene pressures. MgCl2/MCM-41 composite supports and the catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption analysis (BET), and elemental analysis. The copolymers were fractionated by extraction with boiling n-heptane, and comonomer contents of the fractions were determined. Under 4 bar ethylene pressure, the bi-supported catalysts showed higher activity and a stronger comonomer activation effect than the TiCl4/MgCl2 catalyst. In comparison with the TiCl4/MgCl2 catalyst, the bi-supported catalysts produced much less copolymer fraction of low molecular weight and high 1-hexene content, meaning that the active center distribution of the catalyst was significantly changed by introducing MCM-41 in the support. The copolymer produced by the bi-supported catalysts showed similar melting temperature to that produced by TiCl4/MgCl2 under the same polymerization conditions. The space confinement effect of the mesopores of MCM-41 on the size and structure of MgCl2 crystallites is proposed as the main reason for the special active center distribution of the bi-supported catalysts.

scholarly journals Preparation of Organic-Inorganic Hybrid Materials Based on MCM-41 and Its Applications

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Sana M. Alahmadi ◽  
Sharifah Mohamad ◽  
Mohd Jamil Maah
Keyword(s):  
Mesoporous Silica ◽  
Nitrogen Adsorption ◽  
Toluene Diisocyanate ◽  
Covalent Attachment ◽  
X Ray Diffraction ◽  
Channel System ◽  
Modification Process ◽  
Adsorption Analysis ◽  
The Fourier Transform ◽  
Mcm 41

This work reports the covalent attachment of three different calix[4]arenes (calix[4]arene (C4), p-sulfonatocalix[4]arene (C4S), and p-tert-butyl-calix[4]arene (PC4)) to MCM-41, using a three-step modification process. 3-Chloropropyltrimethoxysilane (ClPTS) was first attached to the mesoporous silica surface and subsequently converted to amides via the reaction with toluene diisocyanate (TDI). Finally, calix[4]arene derivatives attached to the isocyanate ending remained available on toluene di-iso-cyanate. Changes in the surface properties of the mesoporous silica caused by the chemical modification were monitored using the Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA), and elemental analysis. The FTIR spectra and TGA analysis verify that the calix[4]arene derivatives are covalently attached to the mesoporous silica. The preservation of the MCM-41 channel system was checked by the X-ray diffraction and nitrogen adsorption analysis. These materials were then used to evaluate the sorption properties of some organotins compounds (Tributyltin (TBT), Triphenyltin (TPT), and Dibutyltin (DBT)).

The Adsorption and Chemistry of Tripropyl phosphate (TPP) into Microporous and Mesoporous NaX Zeolites

2011 ◽  
Vol 1304 ◽  
Author(s):  
Qingguo Meng ◽  
David C. Doetschman ◽  
Apostolos K. Rizos ◽  
Min-Hong Lee ◽  
Jürgen T. Schulte ◽  
...  
Keyword(s):  
Solid State ◽  
Structural Properties ◽  
Nmr Spectra ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nax Zeolite ◽  
Stoichiometric Amount ◽  
Polydiallyldimethylammonium Chloride ◽  
Adsorption Analysis

ABSTRACTAdsorption and chemistry of tripropylphosphate (TPP) in mesoporous NaX zeolite, which was templated by cationic templated polymer (polydiallyldimethylammonium chloride, PDADMAC) with two different length chains, was investigated. The structural properties of the zeolites were characterized by X-ray diffraction (XRD) and nitrogen adsorption analysis. The chemical activities of different zeolites toward the decomposition of TPP were determined with solid state 31P NMR spectra. After exposure of zeolites to TPP was sufficient and equilibrium was reached, a stoichiometric amount of water was also adsorbed and hydrolysis was observed. The TPP decomposition yields in different NaX zeolites were compared.

Determination of the Lamellar Phase Content in MCM-41 Using X-ray Diffraction, Nitrogen Adsorption, and Thermogravimetry

2000 ◽  
Vol 104 (7) ◽  
pp. 1581-1589 ◽  
Author(s):  
Michal Kruk ◽  
Mietek Jaroniec ◽  
Yong Yang ◽  
Abdelhamid Sayari
Keyword(s):  
Nitrogen Adsorption ◽  
Lamellar Phase ◽  
Phase Content ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mcm 41

Catalytic Activity of Argentum-loaded MCM-41 for Ozonation of p- Chlorobenzoic Acid (p-CBA) in Aqueous Solution

2015 ◽  
Vol 18 (1) ◽  
Author(s):  
Zhaoqi Pan ◽  
Junyu Zeng ◽  
Bingyan Lan ◽  
Laisheng Li
Keyword(s):  
Aqueous Solution ◽  
Nitrogen Adsorption ◽  
Hexagonal Structure ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Chlorobenzoic Acid ◽  
Transmission Electron ◽  
Initial Ph ◽  
Adsorption Desorption ◽  
Mcm 41

AbstractArgentum-loaded MCM-41 (Ag/MCM-41) was synthesized successfully by a hydrothermal method and used as a catalyst for the ozonation of p-chlorobenzoic acid (p-CBA) in aqueous solution. Ag/MCM-41 was characterized by low angle X-ray diffraction (XRD), nitrogen adsorption-desorption and transmission electron microscopy (TEM). Characterizations suggest that the prepared samples retained a highly regulated mesopores of hexagonal structure and a high BET surface area. The influences of argentum content, initial pH, reaction temperature on the catalytic ozonation were also evaluated. Ag/MCM-41/O

Synthesis and Characterization of Mesoporous Molecular Sieve Al-MCM-41 Using Kaolin as Raw Material

2013 ◽  
Vol 779-780 ◽  
pp. 201-204
Author(s):  
Miao Li ◽  
Hong Wang ◽  
Xian Qing Li ◽  
Jin Rong Liu
Keyword(s):  
Molecular Sieve ◽  
Nitrogen Adsorption ◽  
Mesoporous Molecular Sieve ◽  
Raw Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Adsorption Desorption ◽  
Calcined Kaolin ◽  
Mcm 41

Ordered hexagonally mesoporous molecular sieve Al-MCM-41 with Si/Al (atom) ratio=9 was prepared by hydrothermal synthesis using raw kaolin. X-ray diffraction (XRD), Nitrogen adsorption desorption, Transmission Electron Microscope (TEM) and Energy Dispersive X-ray Detector (EDX) were employed to characterise raw kaolin, calcined kaolin, as-synthesized and calcined Al-MCM-41. The results indicated that characteristic reflections of raw kaolin disappeared after calcination, both of as-synthesized and calcined Al-MCM-41 exhibited well ordered hexagonally mesoporous molecular sieve structure.

Porous Ceramic Humidity Sensors Using Sol-Gel Processed ZrTiO4 Nanoparticles

2006 ◽  
Vol 45 ◽  
pp. 1803-1808 ◽  
Author(s):  
I.C. Cosentino ◽  
E.N.S. Muccillo ◽  
F.M. Vichi ◽  
R. Muccillo
Keyword(s):  
Porous Ceramic ◽  
Mercury Porosimetry ◽  
Sol Gel ◽  
Average Particle Size ◽  
Nitrogen Adsorption ◽  
Zirconium Oxychloride ◽  
Average Particle ◽  
Titanium Tetraisopropoxide ◽  
X Ray Diffraction ◽  
Adsorption Analysis

Ceramic ZrTiO4 powders were prepared by a sol-gel method using zirconium oxychloride and titanium tetraisopropoxide. In situ high temperature X-ray diffraction results show that crystallization of the amorphous gel starts at 400°C. Single-phase ZrTiO4 nanoparticles of 46 nm average particle size, determined by nitrogen adsorption analysis, were obtained after heat treatment at 450°C for 1 h. After pressing these sinteractive powders, pellets with controlled pore size distribution were obtained by sintering at temperatures as low as 400°C. The analysis of pores by mercury porosimetry gives an average porosity of 45%. The electrical resistivity, determined by impedance spectroscopy measurements at 24°C under different humidity environments, shows the ability of these pellets to adsorb water vapor in the porous surfaces.

Textural features of highly ordered Al-MCM-41 molecular sieve studied by X-ray diffraction, nitrogen adsorption and transmission electron microscopy

2006 ◽  
Vol 60 (21-22) ◽  
pp. 2682-2685 ◽  
Author(s):  
Marcelo J.B. Souza ◽  
Antonio S. Araujo ◽  
Anne M.G. Pedrosa ◽  
Bojan A. Marinkovic ◽  
Paula M. Jardim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Sieve ◽  
Nitrogen Adsorption ◽  
Textural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Mcm 41

scholarly journals Supercritical Solvent Impregnation of Different Drugs in Mesoporous Nanostructured ZnO

Pharmaceutics ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 340 ◽  
Author(s):  
Banchero ◽  
Mohamed ◽  
Leone ◽  
Lopez ◽  
Ronchetti ◽  
...  
Keyword(s):  
Drug Loading ◽  
Nitrogen Adsorption ◽  
Water Soluble ◽  
X Ray Diffraction ◽  
Supercritical Solvent ◽  
Adsorption Analysis ◽  
Water Soluble Drugs ◽  
Nanoparticle Morphology ◽  
Amorphous Drug ◽  
First Time

Supercritical solvent impregnation (SSI) is a green unconventional technique for preparing amorphous drug formulations. A mesoporous nanostructured ZnO (mesoNsZnO) carrier with 8-nm pores, spherical-nanoparticle morphology, and an SSA of 75 m2/g has been synthesized and, for the first time, subjected to SSI with poorly water-soluble drugs. Ibuprofen (IBU), clotrimazole (CTZ), and hydrocortisone (HC) were selected as highly, moderately, and poorly CO2-soluble drugs. Powder X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, nitrogen adsorption analysis, and ethanol extraction coupled with ultraviolet spectroscopy were employed to characterize the samples and quantify drug loading. Successful results were obtained with IBU and CTZ while HC loading was negligible, which could be related to different solubilities in CO2, drug size, and polarity. Successful SSI resulted in amorphous multilayer confinement of the drug. The mesoNsZnO-IBU system showed double drug loading than the mesoNsZnO-CTZ one, with a maximum uptake of 0.24 g/g. Variation of contact time during SSI of the mesoNsZnO-IBU system showed that drug loading triplicated between 3 and 8 h with an additional 30% increment between 8 h and 24 h. SSI did not affect the mesoNsZnO structure, and the presence of the adsorbed drug reduced the chemisorption of CO2 on the carrier surface.

Grafting of the Organic Functional Groups to the Iron Nanoparticles Surface via Arenediazonium Tosylates

2014 ◽  
Vol 1040 ◽  
pp. 309-313 ◽  
Author(s):  
O.A. Guselnikova ◽  
M.V. Gromov ◽  
A.I. Galanov
Keyword(s):  
Functional Groups ◽  
Iron Nanoparticles ◽  
Nitrogen Adsorption ◽  
Nanoscale Materials ◽  
X Ray Diffraction ◽  
Adsorption Analysis ◽  
Size Stability ◽  
Ft Ir ◽  
Zero Valent Iron Nanoparticles ◽  
Potential Use

The nanoscale materials and their application have received considerable attention for the last few years owing to its potential use in biomedical fields of science and technology. Recent studies have demonstrated the ability of arenediazoniumtosylates (ADTs) to modify nanoscale materials. An efficient method of modifying zero-valent iron nanoparticles using ADT with different functional organic groups in a water suspension at the room temperature has been developed. Particle composition, size, stability and possible functionalization with ADT have been characterised by using the FT-IR and X-ray diffraction methods, the low-temperature nitrogen adsorption analysis (BET), TGA/DSC/DTA analyses in the air and the elemental analysis. The obtained methods and results are to foster better understanding of nanoparticles modification process and contribute to its further research and development due to the ability of changing functional groups in the ADT molecule for medical and other applications. Variation of the functional groups in the ADT molecule can change the properties of Fe-NPs and predetermine the field of their use.

Sign in / Sign up

Export Citation Format

Share Document