Conversion of Multicyclic Hydrocarbons to Mono-Aromatic Hydrocarbons Over CoMo/Zeolite Socony Mobil-5 Catalysts

2021 ◽  
Vol 21 (7) ◽  
pp. 3819-3823
Author(s):  
Huiji Ku ◽  
Seung Kyo Oh ◽  
Kyuri Kim ◽  
Young-Kwon Park ◽  
Jong-Ki Jeon
Keyword(s):  
Fixed Bed ◽  
Chemical Properties ◽  
Strong Acid ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Weak Acid ◽  
Fixed Bed Reactor ◽  
Nanoporous Structure ◽  
Bead Type ◽  
Catalytic Cracking Reaction

This study focuses on analyzing the effects of the SiO2/Al2O3 ratio of a support on the physico-chemical properties of bead-type CoMo/HZSM-5 catalysts and on the catalytic performance during the hydrocracking reaction of PFO. CoMo/HZSM-5 catalysts were prepared by an incipient wetness method. Subsequently, binder-added catalysts were molded into the bead type catalysts. The N2 adsorption-dersorption results clearly indicate that the nanoporous structure was well developed in the bead-type CoMo/HZSM-5 catalyst. The CoMo/HZSM-5(30) catalyst not only possessed the highest number of acid sites but also showed the highest ratio of strong acid to weak acid sites. Moreover, the Lewis acid/Brönsted acid site ratio is highest with the CoMo/HZSM-5(30) catalysts. A hydrocracking reaction of PFO over the bead-type CoMo/HZSM-5 catalysts was conducted at 400 °C and under 40 atm in a fixed-bed reactor. The bead-type CoMo/HZSM-5(30) catalyst showed the highest BTXE yield with a sum of BTXE outcome of 43.0% in the catalytic cracking reaction of PFO, which is attributed to the synergistic combination of suitable acidity and hierarchical porosity.

scholarly journals Methanol Dehydration to Dimethyl Ether over Modified γ-Al2O3 with Acid, Base and Zeolite (NaA and NaX)

2020 ◽  
Vol 20 (2) ◽  
pp. 109
Author(s):  
Maria Ulfah ◽  
Hendra Suherman ◽  
Melia Laniwati ◽  
IGBN Makertihartha ◽  
Subagjo Subagjo
Keyword(s):  
Surface Acidity ◽  
Fixed Bed ◽  
Strong Acid ◽  
Acid Sites ◽  
Weak Acid ◽  
Fixed Bed Reactor ◽  
Methanol Dehydration ◽  
Zeolite Nax ◽  
Zeolite Naa ◽  
Strong Acid Sites

The effect of acids, bases, zeolite NaA and zeolite NaX impregnation to g-Al2O3 on the catalyst characteristics and activity against methanol dehydration reaction were investigated. The catalyst characteristics include N2 physisorption, X-ray diffraction (XRD), and temperature-programmed desorption of ammonia (NH3-TPD) in addition to catalytic dehydration of methanol performed in a micro fixed-bed reactor at 270°C and 1 atm. The results of XRD characterization showed no changes related to the modification of alumina over acids, bases, and zeolite NaA and zeolite NaX. Therefore, the modification did not have any effect on the crystalline structure of alumina. The textural and surface acidity of g-Al2O3 changed post addition of acids, bases, zeolite NaA and zeolite NaX. NH3-TPD analysis results demonstrated that synthesized g-Al2O3 has three types of acid sites: weak, medium, and strong; however, the weak acid sites were not observed on alumina catalysts modified phosphate, KOH, zeolite NaA, and zeolite NaX. Furthermore, the concentration of strong acid sites increased in the catalyst containing KOH. The catalytic test results showed that the untreated g-Al2O3 catalyst gave prominent activity in dehydration of methanol compared to the treated catalyst following the number and strength of acid sites. 

Reaction Mechanism for CCl2F2 Catalytic Decomposition over MoO3/ZrO2

2013 ◽  
Vol 295-298 ◽  
pp. 326-330 ◽  
Author(s):  
Tian Cheng Liu ◽  
Yu Jiao Guo ◽  
Ping Ning ◽  
Ming Long Yuan
Keyword(s):  
Reaction Mechanism ◽  
Main Product ◽  
Solid Acid ◽  
Fixed Bed ◽  
Catalytic Decomposition ◽  
Strong Acid ◽  
Acid Sites ◽  
Fixed Bed Reactor ◽  
Surface Intermediate ◽  
Strong Acid Sites

Catalytic hydrolysis decomposition of dichlorodifluoromethane (CCl2F2) in the presence of water vapor and oxygen was studied over a series of solid acids using a fixed-bed reactor. Solid acid MoO3/ZrO2 displayed the highest activity, over which the conversion of CCl2F2 reached 100 % at 250 °C. CO2 was the main-product and the selectivity to CClF3 remained lower than 28.0 %. CO was not detected as by-product. The decomposition activity depended on the calcination temperature and the ZrO2 content. The activity of solid acid MoO3/ZrO2 correlates well with its specific surface area and the amount of medium-strong acid sites on the surface. To explain the reaction mechanism for CCl2F2 catalytic decomposition over MoO3/ZrO2, a surface intermediate, Osurface-CF2-Osurface is proposed.

Effect of Hydrothermal Conditions on Isomerization Activity of Pt/SO42--ZrO2

2010 ◽  
Vol 132 ◽  
pp. 183-191
Author(s):  
Juan Juan Zhang ◽  
Yue Qin Song ◽  
Xiao Long Zhou ◽  
Cheng Lie Li ◽  
Jin An Wang ◽  
...  
Keyword(s):  
Sulfur Content ◽  
Crystalline Structure ◽  
Fixed Bed ◽  
Strong Acid ◽  
Acid Sites ◽  
Zirconium Hydroxide ◽  
Fixed Bed Reactor ◽  
Isomerization Reaction ◽  
Hydrothermal Conditions ◽  
Hydrous Zirconia

Pt/SO42--ZrO2 catalysts (PSZ) were prepared by using a series of hydrous zirconia as support synthesized via a hydrothermal method. The catalytic performances of these catalysts were evaluated in the n-hexane isomerization in a fixed bed reactor. The crystalline structure, acidity, reduction properties, textural texture, and sulfur content were characterized by XRD, NH3-TPD, H2-TPR, N2 adsorption and thermal analysis. The experimental results indicated that the hydrothermal ageing of zirconium hydroxide led to great changes in the crystalline structure of hydrous zirconia support, sulfur content, and the acidity of PSZ. The abundant strong acid sites and high sulfur content were essential but insufficient to achieve a PSZ catalyst with high isomerization activity. Too weak or too strong interaction between sulfur species and zirconia in the catalysts was unfavorable to the isomerization reaction. The presence of considerable sulfate species interacting moderately with zirconia was crucial to high isomerization activity.

Coke on HZSM-5/SAPO-34 Catalyst for Ethanol to Propylene

2014 ◽  
Vol 962-965 ◽  
pp. 751-754 ◽  
Author(s):  
Wang Feng ◽  
Bai Ting ◽  
Duan Chao ◽  
Wen Ting Qu ◽  
Xi Ling Liu ◽  
...  
Keyword(s):  
Fixed Bed ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Fixed Bed Reactor ◽  
Coke Deposition ◽  
High Yield ◽  
Active Centers ◽  
Isothermal Adsorption ◽  
Initial Stage ◽  
Adsorption Desorption

The catalytic performance on HZSM-5/SAPO-34 catalyst in ethanol to propylene was tested in continuous-flow fixed-bed reactor. Coke on HZSM-5/SAPO-34 catalyst for ethanol to propylene was studied by O2-TPO, N2isothermal adsorption–desorption and NH3-TPD.The result showed that the strong and medium acid sites were the active centers of coke deposition; Coke mainly deposited in mesoporous and some coke blocked microporous orifice; In the initial stage of reaction, the high yield of propylene may be benefited from coke deposition, which adjusted the acidity and structure of HZSM-5/SAPO-34.

Effect of Steam Treatment on Catalytic Performance of La2O3-HZSM-5 for Methylation of Toluene with Methanol

2012 ◽  
Vol 629 ◽  
pp. 381-385 ◽  
Author(s):  
Jun Hui Li ◽  
Zhong Hua Hu ◽  
Ya Nan Wang ◽  
Hao Xiang ◽  
Zhi Rong Zhu
Keyword(s):  
High Selectivity ◽  
Fixed Bed ◽  
Shape Selectivity ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Fixed Bed Reactor ◽  
Steam Treatment ◽  
By Products ◽  
Poor Stability ◽  
Excellent Catalytic Performance

Methylation of toluene with methanol to synthesize p-Xylene was performed in a fixed-bed reactor. HZSM-5 zeolite as a catalyst was prepared by modification with La2O3. In addition, effect of steam treatment for La2O3-modified HZSM-5 on its catalytic performance was investigated as well. The properties of as-prepared catalysts were characterized by XRD, BET and NH3-TPD. The results indicate that modification with La2O3can narrow the size of HZSM-5 channel effectively. And more than 90% selectivity of p-Xylene is obtained over HZSM-5 with loading of 24% and 30% La2O3. However, above La2O3-modified HZSM-5 with high-selectivity exhibit a poor stability for time on-stream of the methylation reaction. Steam treatment of La2O3-modified HZSM-5 can improve its stability and shape selectivity, decreasing by-products. These effects can be attributed to distortion & narrowing of HZSM-5 channel and reduction of HZSM-5 strong Bronsted acid sites during steam treatment. As a result, the excellent catalytic performance is obtained over 24.0% La2O3-modified HZSM-5 by steam treatment at 773 K for 1.0 h, being 23% conversion of toluene, 93% selectivity of p-Xylene during time on-stream.

Coke on Zn/Hβ Catalyst in Ethanol to Propylene

2014 ◽  
Vol 962-965 ◽  
pp. 719-722
Author(s):  
Wen Ting Qu ◽  
Ting Bai ◽  
Feng Wang ◽  
Xi Ling Liu ◽  
Xin Zhang
Keyword(s):  
Physicochemical Properties ◽  
Continuous Flow ◽  
External Surface ◽  
Fixed Bed ◽  
Strong Acid ◽  
Acid Sites ◽  
Fixed Bed Reactor ◽  
Isothermal Adsorption ◽  
Strong Acid Sites ◽  
Adsorption Desorption

Coke on Zn/Hβ catalyst in ethanol to propylene was studied in continuous-flow fixed-bed reactor. The physicochemical properties of these fresh and used catalysts were characterized by NH3-TPD, N2 isothermal adsorption-desorption and TPO. These results showed that the medium and strong acid sites might be responsible for the production of coke and coke mainly deposited on external surface and microporous mouth. In addition, the coke might be consisted of soft coke and hard coke.

scholarly journals Effect of Catalyst Crystallinity on V-Based Selective Catalytic Reduction with Ammonia

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1452
Author(s):  
Min Seong Lee ◽  
Sun-I Kim ◽  
Myeung-jin Lee ◽  
Bora Ye ◽  
Taehyo Kim ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Fixed Bed Reactor ◽  
Scr Catalysts ◽  
Catalyst Systems ◽  
The One ◽  
No2 Formation

In this study, we synthesized V2O5-WO3/TiO2 catalysts with different crystallinities via one-sided and isotropic heating methods. We then investigated the effects of the catalysts’ crystallinity on their acidity, surface species, and catalytic performance through various analysis techniques and a fixed-bed reactor experiment. The isotropic heating method produced crystalline V2O5 and WO3, increasing the availability of both Brønsted and Lewis acid sites, while the one-sided method produced amorphous V2O5 and WO3. The crystalline structure of the two species significantly enhanced NO2 formation, causing more rapid selective catalytic reduction (SCR) reactions and greater catalyst reducibility for NOX decomposition. This improved NOX removal efficiency and N2 selectivity for a wider temperature range of 200 °C–450 °C. Additionally, the synthesized, crystalline catalysts exhibited good resistance to SO2, which is common in industrial flue gases. Through the results reported herein, this study may contribute to future studies on SCR catalysts and other catalyst systems.

Hydrothermal Modification Effect on the Catalyst for Etherification

2013 ◽  
Vol 805-806 ◽  
pp. 1368-1375
Author(s):  
Xi Ming Yan ◽  
Ming Ke ◽  
Zhao Zheng Song
Keyword(s):  
Active Component ◽  
Fixed Bed ◽  
Strong Acid ◽  
Weak Acid ◽  
Fixed Bed Reactor ◽  
Total Acid ◽  
Surface Areas ◽  
Hydrothermal Modification ◽  
Different Temperatures ◽  
Loading Amount

Etherification of isoamylene with methanol has been carried out over the γ-Al2O3/Hβ catalyst in a fixed bed reactor, catalysts were hydrothermal modified at different temperatures and time. The results show that the appropriate loading amount of active component Hβ is 20%; Hydrothermal modification is an effective way to improve the etherification activity, When γ-Al2O3/20%Hβ catalyst was hydrothermal modified at 573K for 3 hours, the isoamylene conversion is the highest, reach up to 51.95%, about 25% higher than the untreated one. From results of BET, XRD, and NH3-TPD characterization can be seen that hydrothermal modification does not change crystalline structure of the catalyst, but specific surface areas decrease together with pore volume and pore size increase, it also reduced the total acid volume of catalyst and improved the surface acid distribution of weak acid and strong acid.

scholarly journals Facile and Rapid Synthesis of Durable SSZ-13 Catalyst using Choline Chloride Template for Methanol-to-Olefins Reaction

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1250
Author(s):  
Xiongchao Lin ◽  
Sasha Yang ◽  
Xiaojia Li ◽  
Caihong Wang ◽  
Yonggang Wang
Keyword(s):  
Choline Chloride ◽  
Strong Acid ◽  
Methanol Conversion ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Weak Acid ◽  
Rapid Synthesis ◽  
Light Olefin ◽  
Mto Reaction ◽  
Strong Acid Sites

In the current study, a facile and rapid synthesis approach for a SSZ-13 catalyst using choline chloride (CC) as a template was proposed, and the catalytic performance for the methanol-to-olefins (MTO) reaction was examined. With a proper amount of CC addition (i.e., m(CC)/m(SiO2)=0.14), uniform and homogeneously distributed cubic SSZ-13 crystals were obtained within 4 h with lower aggregation. The synthesized catalyst demonstrated excellent porous features with a total specific surface area and mesopore volume of 641.71 m2·g−1 and 0.04 cm3·g−1, respectively. The optimized strong and weak acid sites on SSZ-13 were obtained by regulating the m(CC)/m(SiO2) ratio. The less strong acid sites and a larger amount of weak acid sites in the synthesized catalyst were conducive to the catalytic performance of the MTO reaction under a lower reaction temperature (450 °C). The appropriate acidity and well-developed pore structure of synthesized SSZ-13 could also slow down the carbon deposition rate and, thus, significantly improve the catalytic lifetime of the catalyst. The methanol conversion rate and initial selectivity of light olefin using the synthesized catalyst could maintain over 95% and 50%, respectively, and a lifetime of 172 min was achieved. Although the low olefin selectivity of the synthesized SSZ-13 catalyst was slightly lower than that of the purchased one, its desirable features were thought to have good potential for industrial application.

scholarly journals Comparative Study of Different Acidic Surface Structures in Solid Catalysts Applied for the Isobutene Dimerization Reaction

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1235 ◽  
Author(s):  
José M. Fernández-Morales ◽  
Eva Castillejos ◽  
Esther Asedegbega-Nieto ◽  
Ana Belén Dongil ◽  
Inmaculada Rodríguez-Ramos ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Fixed Bed Reactor ◽  
Catalyst Stability ◽  
Molar Ratio ◽  
Solid Catalysts ◽  
Catalytic Materials ◽  
Materials Used

Dimerization of isobutene (IBE) to C8s olefins was evaluated over a range of solid acid catalysts of diverse nature, in a fixed bed reactor working in a continuous mode. All catalytic materials were studied in the title reaction performed between 50–250 °C, being the reaction feed a mixture of IBE/helium (4:1 molar ratio). In all materials, both conversion and selectivity increased with increasing reaction temperature and at 180 °C the best performance was recorded. Herein, we used thermogravimetry analysis (TGA) and temperature programmed desorption of adsorbed ammonia (NH3-TPD) for catalysts characterization. We place emphasis on the nature of acid sites that affect the catalytic performance. High selectivity to C8s was achieved with all catalysts. Nicely, the catalyst with higher loading of Brønsted sites displayed brilliant catalytic performance in the course of the reaction (high IBE conversion). However, optimum selectivity towards C8 compounds led to low catalyst stability, this being attributed to the combined effect between the nature of acidic sites and structural characteristics of the catalytic materials used. Therefore, this study would foment more research in the optimization of the activity and the selectivity for IBE dimerization reactions.

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