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 Facile and Rapid Synthesis of Durable SSZ-13 Catalyst Using Choline Chloride Template for Methanol-to-Olefins

2021 ◽  
Author(s):  
xiongchao Lin ◽  
Sasha Yang ◽  
Xiaojia Li ◽  
Caihong Wang ◽  
Yonggang Wang
Keyword(s):  
Conversion Rate ◽  
Choline Chloride ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Weak Acid ◽  
Soft Template ◽  
Lower Amount ◽  
Rapid Synthesis ◽  
Light Olefin ◽  
Hexagonal Ring

Abstract In this study, a facile and rapid synthesis approach for SSZ-13 catalyst was proposed using choline chloride (CC) as template. The optimal synthesis condition was explored, and the catalytic performance for methanol-to-olefins (MTO) was examined. Results revealed that the appropriate ratio of soft template could meet the condition for rapid and ordered growth of catalyst crystals. Using environmentally friend and cheaper CC as template could greatly accelerate the formation of bi-hexagonal ring structure in SSZ-13 framework, and it could shorten the synthesis cycle to within 4 h. 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 with relatively lower aggregation. The catalyst synthesized with m(CC)/m(SiO2)=0.14 demonstrated excellent porous features with a total specific surface area and mesopore volume of 641.706 m2.g-1 and 0.0377 cm3.g-1, respectively. The optimized strong and weak acid sites on the SSZ-13 were obtained by regulating the m(CC)/m(SiO2). As a typical acid catalytic reaction, the SSZ-13 catalyst with strong and weak acid sites exhibited bi-functional role. The lower amount of strong acid sites and larger amount of weak acid sites in the synthesized catalyst were conducive to the catalytic performance for MTO under relatively lower reaction temperature (450 oC). Consequently, the synthesized SSZ-13 showed a better conversion rate and lifetime than that of purchased one. The methanol conversion rate using synthesized catalyst was maintained over 95% within 120 min, and its lifetime was achieved to 172 min. The appropriate acidity and well-developed pore structure of synthesized SSZ-13 could slow down the carbon deposition rate and significantly increase the lifetime of the catalyst. Moreover, the initial selectivity of light olefin could maintain above 50% within 160 min. Eventually, the desirable features of synthesized SSZ-13 catalyst were thought be with good potential for industrial application.

Effect of autotransformation on the layer charge of smectites determined by the alkylammonium method

Clay Minerals ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 623-632 ◽  
Author(s):  
M. Janek ◽  
P. Komadel ◽  
G. Lagaly
Keyword(s):  
Aqueous Dispersion ◽  
Strong Acid ◽  
Acid Sites ◽  
Weak Acid ◽  
Layer Charge ◽  
Exchange Method ◽  
Density Distributions ◽  
Titration Curves ◽  
The Mean ◽  
Strong Acid Sites

AbstractHydrogen-forms of <2 µm fractions of six bentonites of various Fe contents were prepared by H+→OH-→H+ ion exchange using resins. Potentiometric titration curves revealed that the number of strong acid sites varied and accounted for 60-95% of the total acidity in the freshly prepared H-forms. The number of strong acid sites decreased and that of the weak acid sites increased on ageing. The process of autotransformation in aqueous dispersion at 90~ was completed within four days. Layer-charge distributions of all samples were inhomogeneous with layer charges from 0.25-0.39 Eq/unit O10(OH)2. Oxalate pretreatment of the samples resulted in changes in the layer-charge distribution due to the removal of readily soluble phases which may have blocked exchange sites. After autotransformation, the alkylammonium exchange method revealed inhomogeneous charge density distributions; the fraction of layers of the highest charge decreased. Comparison of total CEC obtained from potentiometric curves and interlamellar CEC calculated from the mean layer charge confirmed attack of protons from particle edges. However, for several samples the structural attack may also occur from the interlayer space. Autotransformation of the Hsmectites decreased the mean layer charge. Protons probably attack the Mg(O,OH)6 octahedra preferentially during the autotransformation.

scholarly journals Catalytic Rapid Pyrolysis ofQuercus variabilisover Nanoporous Catalysts

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Hyeon Koo Kang ◽  
In-Gu Lee ◽  
Kyong-Hwan Lee ◽  
Beom-Sik Kim ◽  
Tae Su Jo ◽  
...  
Keyword(s):  
Oil Quality ◽  
Strong Acid ◽  
Abundant Species ◽  
Acid Sites ◽  
Weak Acid ◽  
Nanoporous Materials ◽  
Bio Oil ◽  
Strong Acid Sites ◽  
Rapid Pyrolysis ◽  
Mcm 41

Catalytic rapid pyrolysis ofQuercus variabilis, a Korean native tree species, was carried out using Py-GC/MS. Mesoporous MFI, which has both nanopores and micropores, and three nanoporous materials, Al-MCM-41, Al-SBA-15, andγ-Al2O3, were used as the catalyst. The acid sites of mesoporous MFI were strong Brønsted acid sites, whereas those of nanoporous materials were mostly weak acid sites. The composition of the product bio-oil varied greatly depending on the acid characteristics of the catalyst used. Phenolics were the most abundant species in the bio-oil, followed by acids and furanics, obtained over Al-MCM-41 or Al-SBA-15 with weak acid sites, whereas aromatics were the most abundant species produced over mesoporous MFI with strong acid sites, followed by phenolics. Aromatics, phenolics, and furanics are all important chemicals contributing to the improvement of bio-oil quality.

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. 

scholarly journals MIL-101(Cr) for CO2 Conversion into Cyclic Carbonates, Under Solvent and Co-Catalyst Free Mild Reaction Conditions

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 453
Author(s):  
Emmanuelia Akimana ◽  
Jichao Wang ◽  
Natalya V. Likhanova ◽  
Somboon Chaemchuen ◽  
Francis Verpoort
Keyword(s):  
Ring Opening ◽  
High Surface ◽  
High Surface Area ◽  
Strong Acid ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Cyclic Carbonates ◽  
Reaction Conditions ◽  
Co Catalyst ◽  
Strong Acid Sites

Mild reaction conditions (nearly room temperature and atmospheric CO2 pressure) for the cycloaddition of CO2 with epoxides to produce cyclic carbonates were investigated applying MIL-101(Cr) as a catalyst. The MIL-101 catalyst contains strong acid sites, which promote the ring-opening of the epoxide substrate. Moreover, the high surface area, enabling the adsorption of more CO2 (substrate), combined with a large pore size of the catalyst is essential for the catalytic performance. Additionally, epoxide substrates bearing electron-withdrawing substituents or having a low boiling point demonstrated an excellent conversion towards the cyclic carbonates. MIL-101(Cr) for the cycloaddition of carbon dioxide with epoxides is demonstrated to be a robust and stable catalyst able to be re-used at least five times without loss in activity.

scholarly journals Heteropolyacid Salt Catalysts for Methanol Conversion to Hydrocarbons and Dimethyl Ether: Effect of Reaction Temperature

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 320 ◽  
Author(s):  
Yuehong Yu ◽  
Daoming Sun ◽  
Shuanjin Wang ◽  
Min Xiao ◽  
Luyi Sun ◽  
...  
Keyword(s):  
Copper Ions ◽  
Strong Acid ◽  
Methanol Conversion ◽  
Acid Sites ◽  
Light Olefins ◽  
Acid Salt ◽  
Silicotungstic Acid ◽  
Different Temperatures ◽  
Light Olefins Selectivity ◽  
Strong Acid Sites

Phosphotungstic and silicotungstic acid salt catalysts (CuPW, CuSiW, FePW, FeSiW) were synthesized by substitution of protons with ferric and copper ions through a simple replacement reaction. The structure and thermal stability were characterized by IR, XRD and TG, and the salts showed a keggin structure and a thermal tolerance near 450 °C. Temperature programmed reactions indicated that the four catalysts showed similar trends in the change of methanol conversion, DME selectivity, and light olefins selectivity at 100–400 °C. Copper salt catalysts showed a 100% DME selectivity at temperatures ranging from 100–250 °C, while FeSiW and FePW catalysts had a 100% DME selectivity near 250 °C. Moreover, the heteropolyacid salt catalysts also produced a certain number of light olefins at the temperature ranging from 250–350 °C, and the CuSiW catalyst exhibited the highest ethylene and propylene selectivity of 44%. In the stability test evaluated at 200 °C, the catalysts showed different tendencies during the induction period and the same trends during the reduction period for the methanol conversion to DME, due to the differences in the strengths of the strong acid sites. Finally, the silicotungstic acid salt catalysts showed the longest lifetime of 120 h, much longer than the heteropolyacids. This approach provides an effective way to synthesize hydrocarbons through methanol, especially DME, at different temperatures using one catalyst.

scholarly journals Insights over Titanium Modified FeMgOx Catalysts for Selective Catalytic Reduction of NOx with NH3: Influence of Precursors and Crystalline Structures

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 560 ◽  
Author(s):  
Liting Xu ◽  
Qilei Yang ◽  
Lihua Hu ◽  
Dong Wang ◽  
Yue Peng ◽  
...  
Keyword(s):  
Mixed Oxides ◽  
Catalytic Reduction ◽  
Strong Acid ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Side Reactions ◽  
Amorphous Iron ◽  
Nox Conversion ◽  
Surface Active ◽  
Strong Acid Sites

Titanium modified FeMgOx catalysts with different precursors were prepared by coprecipitation method with microwave thermal treatment. The iron precursor is a key factor affecting the surface active component. The catalyst using FeSO4 and Mg(NO3)2 as precursors exhibited enhanced catalytic activity from 225 to 400 °C, with a maximum NOx conversion of 100%. Iron oxides existed as γ-Fe2O3 in this catalyst. They exhibited highly enriched surface active oxygen and surface acidity, which were favorable for low-temperature selective catalytic reduction (SCR) reaction. Besides, it showed advantage in surface area, spherical particle distribution and pores connectivity. Amorphous iron-magnesium-titanium mixed oxides were the main phase of the catalysts using Fe(NO3)3 as a precursor. This catalyst exhibited a narrow T90 of 200/250–350 °C. Side reactions occurred after 300 °C producing NOx, which reduced the NOx conversion. The strong acid sites inhibited the side reactions, and thus improved the catalytic performance above 300 °C. The weak acid sites appeared below 200 °C, and had a great impact on the low-temperature catalytic performance. Nevertheless, amorphous iron-magnesium-titanium mixed oxides blocked the absorption and activation between NH3 and the surface strong acid sites, which was strengthened on the γ-Fe2O3 surface.

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 Hierarchy in zeolite catalysis: The influence of enhanced mesoporosity on the synthesis of renewable fuels and bio-based platform chemicals

2020 ◽  
Vol 10 (4) ◽  
pp. 217-232
Author(s):  
Aqeel Al-Ani ◽  
Catia Freitas ◽  
Vladimir Zholobenko
Keyword(s):  
Oleic Acid ◽  
Active Sites ◽  
Strong Acid ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Zeolite Catalysis ◽  
Chemical Treatments ◽  
Platform Chemicals ◽  
Fau Zeolite ◽  
Strong Acid Sites

Faujasite (FAU), ZSM-5 (MFI), beta (BEA) and mordenite (MOR) zeolites were admitted to a variety of chemical treatments accompanied by surfactant templating strategy, aiming to introduce the intracrystalline mesoporosity effectively. The resulting materials were tested as solid acid catalysts for esterification of the oleic acid as a common model impurities found in bio-oil feedstoks. It was found that the esterification of oleic acid can be enhanced by the presence of strong acid sites in zeolites and their improved accessibility. Overall, mesostructured FAU zeolite demonstrated an improved catalytic performance as a result of increasing accessibility of the zeolite active 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.

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