Study and Fabrication of Acid-Modified Diatomite

2012 ◽  
Vol 512-515 ◽  
pp. 2175-2178
Author(s):  
Yan Jiang ◽  
Hua Ye ◽  
Li Na He
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Acid Treatment ◽  
Great Increase ◽  
Acid Modification ◽  
Catalyst Carrier ◽  
Modification Process ◽  
Large Mesopores ◽  
Potential Use ◽  
Modified Diatomite

This paper presents an investigation of the purification and activation of a raw diatomite by acid treatment. In the acid modification process, the SiO2 gel powder was adsorbed partially into the pure diatomite, blocking macropores and large mesopores of diatomite, which resulted in great increase of the specific surface area and SiO2 content of diatomite. Thus, the as-prepared diatomite has potential use in the fabrication of catalyst carrier.

scholarly journals Acid Modification of the Unsupported NiMo Catalysts by Y-Zeolite Nanoclusters

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 344
Author(s):  
Chengwu Dong ◽  
Changlong Yin ◽  
Tongtong Wu ◽  
Zhuyan Wu ◽  
Dong Liu ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Average Pore Size ◽  
Y Zeolite ◽  
Active Components ◽  
Acid Modification ◽  
Total Acid ◽  
Average Pore ◽  
Nimo Catalysts

Unsupported NiMo catalyst has high hydrogenation activity due to its high active site distribution. However, low specific surface area and pore distribution greatly limit the efficient utilization of the active components. The Y-zeolite nanoclusters were hydrothermally synthesized and introduced into the unsupported NiMo catalysts from a layered nickel molybdate complex oxide. The XRD, N2 adsorption-desorption, FT-IR, Py-IR, SEM, NH3-TPD, and TEM were used to characterize all catalysts. The dibenzothiophene (DBT) hydrodesulfurization (HDS) reaction was performed in a continuous high pressure microreactor. The results showed that the specific surface area, pore volume, and average pore size of the unsupported NiMo catalysts were greatly increased by the Y-zeolite nanoclusters, and a more dispersed structure was produced. Furthermore, the Lewis acid and total acid content of the unsupported NiMo catalysts were greatly improved by the Y-zeolite nanoclusters. The HDS results showed that the unsupported NiMo catalysts modified by the nanoclusters had the same high desulfurization efficiency as the unmodified catalyst, but had more proportion of direct desulfurization (DDS) products. The results offer an alternative to reducing hydrogen consumption and save cost in the production of ultra clean diesel.

Influence of Acid Treatment on the Loading and Release Behavior of Halloysite with 2-Mercaptobenzothiazole

2019 ◽  
Vol 19 (11) ◽  
pp. 7178-7184 ◽  
Author(s):  
Xuteng Xing ◽  
Jihui Wang ◽  
Qiushi Li ◽  
Wenbin Hu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Acid Treatment ◽  
Gas Adsorption ◽  
Treatment Time ◽  
Halloysite Nanotubes ◽  
Tubular Structure ◽  
Internal Diameter ◽  
Release Behavior

Halloysite nanotubes (HNTs) are natural clay minerals with a tubular structure. They have attracted considerable attention as a potential nanocontainer due to their abundance, biocompatibility and nontoxicity. In this study, HNTs were handled with H2SO4 at 70 °C. The morphology and structure of these acid-treated and original HNTs were investigated by scanning electron microscopy (SEM), energy dispersion spectrum (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), and their specific surface area was determined by automatic gas adsorption analyzer. The loading efficiency and release behavior of acid-treated HNTs for 2-Mercaptobenzothiazole (MBT) were investigated by UV-vis spectrophotometer. Results show that acid-treated HNTs retained their tubular structure, but their internal diameter expanded by 35–37 nm after 32 h of acid treatment. After 72 h of acid treatment, HNTs can be transferred into amorphous silica nanotubes. Moreover, the specific surface area of these HNTs samples initially increased with the increase in acid treatment time but then started to decrease after 32 h. The specific surface area of acid-treated HNTs at 32 h can reach 251.6 m2/g, which was much higher than that for untreated HNTs (55.3 m2/g). In addition, the loading capacity of acid-treated HNTs can reach 32.1% for HNTs-32, which is about three times higher than that of original HNTs. The acid treatment has slight effect on the release behavior.

Modification of Cordierite Honeycomb Ceramics Matrix for DeNOx Catalyst

2012 ◽  
Vol 1449 ◽  
Author(s):  
Qingcai Liu ◽  
Yuanyuan He ◽  
Jian Yang ◽  
Wenchang Xi ◽  
Juan Wen ◽  
...  
Keyword(s):  
Acid Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Acid Treatment ◽  
Coefficient Of Thermal Expansion ◽  
Physical Adsorption ◽  
Active Species ◽  
Treatment Temperature ◽  
Cordierite Honeycomb

ABSTRACTTo obtain highly dispersed and highly active catalysts by impregnating of active species onto the monolith directly, cordierite honeycomb ceramics were modified by nitric acid solution of 68wt%. Effects of acid treatment temperature and time on the performance of cordierite were investigated. Specific surface area, pore size distribution, morphology and structure of cordierite were characterized by N2-physical adsorption, SEM, XRD, respectively. Concentrations of ions in the acid solution were measured by AAS. It is shown that the corrosion content of cordierite increases and more micropores are generated with increasing time of acid treatment, leading to an upward trend of specific surface area. The coefficient of thermal expansion and compression strength decrease obviously at a higher temperature, which is mainly attributed to the removal of Al and Mg ions from the silicate structure and delayed formation of free amorphous silica on the surface of the cordierite. The optimal modification process of cordierite matrix acid erosion is at 110°C for 6 h.

scholarly journals Acid Modification of Diatomite-Based Sorbents

2020 ◽  
Vol 22 (3) ◽  
pp. 157
Author(s):  
A. Nurgain ◽  
M. Nazhipkyzy ◽  
A.A. Zhaparova ◽  
A.T. Issanbekova ◽  
M. Alfe ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Acid Modification ◽  
Acid Pretreatment ◽  
Specific Pore Volume ◽  
Calcination Temperatures ◽  
Pre Treatment ◽  
Hcl Concentration

In this work, the effect of acid pre-treatment (hydrochloric acid, HCl) and calcination of diatomite, a silicon dioxide-material from natural sources, was studied with the aim to obtain diatomite-based sorbents with specific physicochemical properties. For this, acid pre-treatments with HCl at different calcination conditions, namely HCl concentration (0.5, 1 M) and calcination temperatures (from 600 to 900 °C) were studied. Morphological features different from those of natural diatomite were obtained. It has been found that treatment of diatomite with 0.5 M HCl at 800 °C showed a specific pore volume of 0.008 cm3/g, and a specific surface area of 19.26 m2/g, while the treatment of diatomite with 1.0 M HCl showed a specific pore volume of 0.011cm3/g, and a specific surface area of 25.57 m2/g. The performance of the acid pretreatment of diatomite for adsorption of Pb ions from water was also studied.

Preparation and characterization of porous cordierite for potential use in cellular ceramics

2009 ◽  
Vol 63 (4) ◽  
Author(s):  
Marta Valášková ◽  
Gražyna Martynková
Keyword(s):  
Specific Surface ◽  
Size Distribution ◽  
Surface Area ◽  
Aluminum Hydroxide ◽  
Specific Surface Area ◽  
Porous Ceramics ◽  
High Porosity ◽  
Cordierite Ceramics ◽  
Potential Use

AbstractCordierite porous ceramics Z, X, and K were prepared using three mixtures of clay minerals: Z from kaolinite, talc, and aluminum hydroxide, X from kaolinite, talc, vermiculite, and aluminum hydroxide, and K from kaolinite, talc, and magnesium oxide. Ceramics were different in porosity, specific surface area, cordierite polymorphs, and secondary crystalline phases. Vermiculite influenced textural architecture of calcined cordierite ceramics X and predestinated crystallization of the high-temperature hexagonal α-cordierite with secondary minerals enstatite, spinel and corundum. Ceramics Z contained low-temperature orthorhombic β-cordierite, enstatite, and corundum, K was diphase of β-cordierite and forsterite. Total pore area (TPA) and specific surface area (SSA) of X, in spite of the higher porosity and the pore size distribution in the range of 300–1000 nm, were smaller in comparison with TPA and SSA of Z. Ceramics K retained high porosity, two maxima at 300–1000 nm and 50–200 nm in the pores size distribution, and the highest TPA and SSA compared to those observed in ceramics Z and X.

scholarly journals Textural and structural modifications of saponite from Cerro del Aguila by acid treatment

Clay Minerals ◽  
2001 ◽  
Vol 36 (4) ◽  
pp. 483-488 ◽  
Author(s):  
M. Suárez Barrios ◽  
C. de Santiago Buey ◽  
E. García Romero ◽  
J. M. Martín Pozas
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Acid Treatment ◽  
Active Sites ◽  
Internal Surface ◽  
Acid Activation ◽  
Acid Attack ◽  
Surface Areas ◽  
Treated Sample

AbstractThe physicochemical properties of clays can be modified by acid treatment with inorganic acids. This treatment is usually referred to as ‘acid activation’, because it increases the specific surface area and the number of active sites of the solids. In the present study, the acid activation of saponite from Cerro del Aguila (Madrid, Spain) with HCl solutions was measured. Illite, quartz and small amounts of feldspar were found as impurities in the raw saponite.Acid treatments were carried out with different concentrations of HCl solutions. The samples obtained were characterized by mineralogical and chemical analyses, XRD, FT-IR spectroscopy, N2 adsorption-desorption isotherms and TEM. The acid attack, under the conditions employed, produced a progressive destruction of the structure of saponite by partial dissolution of the octahedral Mg(II) cations. Amorphous silica coming from the tetrahedral sheet of saponite was generated. The specific surface area of the most intensely treated sample (2.5% for 24 h) was doubled with respect to that of natural saponite. This increase in the surface area is due to the increase in both the external and internal surface areas.

scholarly journals Effect of Acid Treatment on the Properties of Zeolite Catalyst for Straight-Run Gasoline Upgrading

2021 ◽  
Vol 1 (4) ◽  
pp. 1-1
Author(s):  
Ludmila Velichkina ◽  
◽  
Yakov Barbashin ◽  
Alexander Vosmerikov ◽  
◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Acid Treatment ◽  
Catalytic Properties ◽  
Fixed Bed ◽  
Acid Sites ◽  
Gasoline Fraction ◽  
Zeolite Catalysts ◽  
Acidic Properties

The objective of this research was to analyze the effect of different concentrations of nitric and hydrochloric acids on the structural, acidic, and catalytic properties of a post-synthetic treated ZSM-5 type zeolite at various temperatures. The properties of zeolite catalysts were determined using different methods, such as the Brunauer-Emmett-Teller (BET) method for specific surface area, temperature-programmed desorption (TPD) of ammonia method for acidic properties, and a flow-through unit with fixed bed catalyst (with upgrading straight-run gasoline fraction of oil) for catalytic activities of initial zeolite and acid-treated samples. The structural and acidic properties of both untreated and treated zeolites were investigated, and the effect of acid treatment on the catalytic properties of the samples in the course of upgrading the straight-run gasoline fraction of oil was determined. The post-synthetic treatment with aqueous nitric acid increased the specific surface area and volume of micropores of ZSM-5 zeolite, while the treatment with aqueous hydrochloric acid led to the formation of mesopores. Acid treatments of zeolite decreased the number of acid sites, mainly due to diminished concentration of low-temperature sites. The yield of liquid products in the conversion of straight-run gasoline fraction of oil, i.e., generation of high-octane gasolines with improved environmental features, was increased using acid-treated zeolites, which was due to the decrease in arene content.

Dimethyl Ether Catalytic Combustion over Manganese Oxides with Different Structures

2010 ◽  
Vol 146-147 ◽  
pp. 1482-1485 ◽  
Author(s):  
Lin Yu ◽  
Gui Qiang Diao ◽  
Fei Ye ◽  
Ming Sun ◽  
Yue Liu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Dimethyl Ether ◽  
Specific Surface Area ◽  
Acid Treatment ◽  
Catalytic Combustion ◽  
Manganese Oxides ◽  
Mn Species

α-MnO2, β-MnO2 and Mn2O3 were synthesized from birnessite followed by acid treatment and subsequently calcined under different conditions. These catalysts were used for catalytic combustion of dimethyl ether (DME) and characterized by XRD, BET and H2-TPR techniques. The results showed that the catalytic activity of α-MnO2, β-MnO2 and Mn2O3 are higher than that of birnessite. Larger specific surface area as well as the better reducibility of Mn species in the manganese oxides might be the main contribution for the DME combustion activity.

scholarly journals Modification of Bentonite with Cationic and Nonionic Surfactants: Structural and Textural Features

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3772 ◽  
Author(s):  
Magdalena Andrunik ◽  
Tomasz Bajda
Keyword(s):  
Specific Surface ◽  
Nonionic Surfactant ◽  
Surface Area ◽  
Clay Minerals ◽  
Cationic Surfactant ◽  
Specific Surface Area ◽  
Nonionic Surfactants ◽  
Inorganic Compounds ◽  
Infrared Spectrometry ◽  
Modification Process

Surfactant-modified clay minerals are known for their good sorption properties of both organic and inorganic compounds from aqueous solutions. However, the current knowledge regarding the effect of both cationic and nonionic surfactants on the properties of bentonite is still insufficient. Bentonite, with montmorillonite as the base clay, was modified with hexadecethyltrimethylammonium bromide (a cationic surfactant) in the amount of 1.0 cation exchange capacity (CEC) of bentonite and varying concentrations of t-octylphenoxypolyethoxyethanol (Triton X-100, a nonionic surfactant). We aimed to improve the understanding of the effect of nonionic and cationic surfactants on clay minerals. The modified bentonites were characterized by X-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TG/DTA), Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (SEM) and specific surface area and pore volume (BET). According to our results, the presence of a cationic surfactant significantly increased the amount of the adsorbed nonionic surfactant. Moreover, an increase in the concentration of nonionic surfactants is also associated with an increase in the effectiveness of the modification process. Our results indicate that the amount of nonionic surfactant used has a significant effect on the properties of the obtained hybrid material. Modification of bentonite with a nonionic surfactant did not cause an expansion of the interlayer space of smectite, regardless of the presence of a cationic surfactant. The modification process was found to significantly decrease the specific surface area of bentonite. Improvement of hydrophobic properties and thermal stability was also observed.

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