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.

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 ZSM-5 Zeolite in order to Improve the Yield of Light Olefins during Cracking of Oil and Plant Materials

2018 ◽  
Vol 18 (4) ◽  
pp. 31-40
Author(s):  
V. P. Doronin ◽  
P. V. Lipin ◽  
O. V. Potapenko ◽  
V. V. Vysotsky ◽  
T. I. Gulyaeva ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Alkali Treatment ◽  
Total Yield ◽  
Acid Sites ◽  
Vacuum Gasoil ◽  
Light Olefins ◽  
Plant Oil ◽  
Plant Materials

The influence of modifying HZSM-5 zeolite as a component of a bizeolite catalyst in transformations of hydrotreated vacuum gasoil, plant oil, and a mixture of vacuum gasoil and plant oil was studied. The modification with phosphorus was established to decrease the specific surface area and meso- and macropore volumes in HZSM-5 zeolite; the higher phosphorus content, the lower main characteristics of the zeolite porous structure. A decrease in the total acidity of P/HZSM-5 and quantitative redistribution between weak and moderate acid sites also was observed. Testing of the zeolites in catalytic cracking revealed that the phosphorus modification favored an increase in the total yield of propane-propylene and butane-butylene fractions containing olefins in high proportions. Alkali treatment of HZSM-4 zeolite with a high silicate module resulted in a higher silicon extraction and in a considerable increase in the specific surface area of mesopores. In addition, strong acid sites of the zeolite were transformed to weaker ones and/or their exposure changed due to partial silicon removal.

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 Modification of natural clinoptilolite and ZSM-5 with different oxides and studying of the obtained products in lignin pyrolysis

2015 ◽  
Vol 80 (5) ◽  
pp. 717-729 ◽  
Author(s):  
Jelena Milovanovic ◽  
Ruth Stensrød ◽  
Elisabeth Myhrvold ◽  
Roman Tschentscher ◽  
Michael Stöcker ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Acid Sites ◽  
X Ray ◽  
Ion Exchange Reaction ◽  
Catalytic Experiment ◽  
Bet Method ◽  
Polycyclic Aromatic ◽  
Natural Clinoptilolite

In this work, different metal oxides (MO) supported on two types of zeolites: 1) natural clinoptilolite (NZ) and 2) synthetic zeolite, ZSM-5 were prepared and tested as catalysts in the fast pyrolysis of hardwood lignin. NZ was modified with the CaO and MgO by a simple two steps procedure consisting of an ion exchange reaction and a subsequent calcination at 773 K. The synthetic ZSM-5 was modified with several MO species (Ni, Cu, Ca, Mg) by a wet impregnation and calcination at 873 K. ?he prepared catalysts were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS) and measurement of specific surface area (BET method). Acid sites were characterized and quantified by pyridine (py) absorption using Fourier transform infrared spectroscopy (FTIR). The catalysts exhibit catalytic activity depanding on modification, reaction temperature and of the MO contents. The highest yield of useful phenol in bio-oil was obtained with NiO/ZSM-5 (34.8 wt.%) which exhibits the highest specific surface area and the highest concetration of Br?nsted and Lewis acid sites. The studied catalysts did not increase significantly the content of polycyclic aromatic hydrocarbons (PAHs) and heavy compounds compared to non-catalytic experiment.

scholarly journals Use of NH4Cl for activation of carbon xerogel to prepare a novel efficacious adsorbent for benzene removal from contaminated air streams in a fixed-bed column

2020 ◽  
Vol 18 (2) ◽  
pp. 1141-1149 ◽  
Author(s):  
Ayoob Rastegar ◽  
Mitra Gholami ◽  
Ahmad Jonidi Jafari ◽  
Ahmad Hosseini-Bandegharaei ◽  
Majid Kermani ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Fixed Bed ◽  
Carbon Aerogel ◽  
Carbon Xerogel ◽  
Fixed Bed Column ◽  
Structure And Morphology ◽  
Benzene Removal ◽  
Air Streams

Abstract Background Ammonium chloride as an explosive salt has proved to be a prominent activation agent for adsorbents and increase the specific surface area and volume of cavities. In this work, the ability of this substance was scrutinized for activation of carbon aerogel to prepare an efficient adsorbent for benzene removal from air streams. Methods A carbon xerogel was fabricated from Novallac polymer and activated by ammonium chloride.The changes in structure and morphology were considered via Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Barrett-Joyner-Halenda (BJH), and energy dispersive X-ray (EDX) analyses. Also, comprehensive studies were conducted to vouchsafe the properties of the new adsorbent for benzene removal, using a fixed-bed column mode. Results The results showed both the successful synthesis and the suitability of the activation process. ACX possessed a higher specific surface area (1008 g/m3), compared to the parent carbon xerogel (CX; 543.7 g/m3) and organic xerogel (OX; 47 g/m3), as well as a higher adsorption capacity. Conclusion NH4CL is a very beneficial for modifying the structure and morphology of carbon aerogel, and the dynamic behavior of the column with respect inlet benzene concentration can be explained by Yan-Nelson model.

Nd-Doped Barium Cerate Nano-Sized Catalyst Converts CH4 into CO2 at Lower Temperature Compared to Noble Metal-Based Pd/Al2O3 Catalyst

2021 ◽  
Vol 10 (3) ◽  
pp. 01-08
Author(s):  
Khalid Ouzaouit ◽  
Abdelhay Aboulaich
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Catalytic Properties ◽  
Area Measurement ◽  
Barium Cerate ◽  
In Situ Ftir Spectroscopy ◽  
Lower Temperature ◽  
Doped Barium Cerate ◽  
Al2o3 Catalyst

The present paper describes the synthesis and first application of Nd-doped BaCeO3 nanoparticles as catalyst for the catalytic oxidation of methane (CH4) into CO2. Nd-doped barium cerate BaCeO3 nanoparticles, with the formula BaNdxCe(1-x)O3, have been prepared using a simple sol gel method starting from acetate precursors. The as-prepared nanoparticles have been fully characterized by XRD, TEM, HRTEM and specific surface area measurement. Results confirmed the formation of highly crystallized nano-sized particles with small crystallite size. In-situ FTIR spectroscopy was used to study the catalytic conversion of methane (CH4) into CO2 in the presence of the as-prepared Nd-doped BaCeO3 nanocatalyst. The catalytic properties of such nanocatalysts have been discussed and correlated to Nd-doping rate, crystallite diameter, and specific surface area of the materials. Excellent catalytic properties have been obtained with BaNd0.05Ce0.95O3, such as, superior conversion efficiency, longer catalysis lifetime and lower activation temperature compared to un-doped BaCeO3 catalyst. Interestingly, it was found that BaNd0.05Ce0.95O3 nanocatalyst successfully converts the totality of CH4 present in a mixture of CH4-Air into CO2 at much lower temperature compared to the conventional Pd/Al2O3 catalyst.

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 Synthesis and Physico-Chemical Characterization of CeO2/ZrO2-SO42- Mixed Oxides

2017 ◽  
Vol 56 (2) ◽  
Author(s):  
Juan Manuel Hernández-Enríquez ◽  
Rebeca Silva-Rodrigo ◽  
Ricardo García-Alamilla ◽  
Luz Arcelia García-Serrano ◽  
Brent Edward Handy ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Synthesis Method ◽  
Chemical Characterization ◽  
Acid Sites ◽  
Oxide Content ◽  
Physico Chemical

Environmentally friendly solid-acid catalysts CeO<sub>2</sub>/ZrO<sub>2</sub>-SO<sub>4</sub><sup>2-</sup> were prepared by the sol gel method varying CeO<sub>2</sub> content (10, 20 and 30 wt%) and using sulfation <em>in situ</em>, maintaining the sulfate ions amount present in the materials at 20 wt%. ZrO<sub>2</sub> and ZrO<sub>2-</sub>SO<sub>4</sub><sup>2-</sup> were also prepared for comparison proposes using the same synthesis method. The materials were characterized by X-ray diffraction, nitrogen physisorption, potentiometric titration with <em>n</em>-butylamine, decomposition of 2-propanol and <em>n</em>-pentane isomerization. The specific surface area of ZrO<sub>2-</sub>SO<sub>4</sub><sup>2-</sup> was high (160 m<sup>2</sup>/g) compared with the unmodified ZrO<sub>2</sub> (80 m<sup>2</sup>/g), however this area decreased with increasing the CeO<sub>2</sub> content (37-100 m<sup>2</sup>/g). There was no significant effect of CeO<sub>2</sub> on the tetragonal structure of ZrO<sub>2-</sub>SO<sub>4</sub><sup>2-</sup>. The variation of acid sites amount runs parallel to the change of specific surface area. The acid sites amount decreased with increasing cerium oxide content. The decomposition of 2-propanol results fundamentally in the formation of dehydration products such as propylene and diisopropyl ether, both involving acid sites. In addition, a good performance during the <em>n</em>-pentane isomerization was observed for these materials. The selectivity towards isopentane reaches 84% when the Pt/CeO<sub>2</sub>/ZrO<sub>2-</sub>SO<sub>4</sub><sup>2-</sup> catalyst with the highest CeO<sub>2</sub> content was used.

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