scholarly journals n-Nonane hydroisomerization over hierarchical SAPO-11-based catalysts with sodium dodecylbenzene sulfonate as a dispersant

2021 ◽  
Vol 18 (2) ◽  
pp. 654-666
Author(s):  
Cheng-Long Wen ◽  
Jun-Dong Xu ◽  
Xue-Man Wang ◽  
Yu Fan
Keyword(s):  
Molecular Sieves ◽  
Amorphous Materials ◽  
External Surface ◽  
Submicron Particles ◽  
Sodium Dodecylbenzene Sulfonate ◽  
Submicron Particle ◽  
External Surface Area ◽  
Dodecylbenzene Sulfonate ◽  
Acid Centers ◽  
High Octane

AbstractTo enhance the gasoline octane number, low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization. Therefore, hierarchical SAPO-11-based catalysts are prepared by adding different contents of sodium dodecylbenzene sulfonate (SDBS), and they are applied in n-nonane hydroisomerization. When n(SDBS)/n(SiO2) is less than or equal to 0.125, the synthesized hierarchical molecular sieves are all pure SAPO-11, and as the SDBS content increases, the submicron particle size decreases, and the external surface area (ESA) increases. Additionally, these hierarchical SAPO-11 have smaller submicron particles and higher ESA values than conventional SAPO-11. When n(SDBS)/n(SiO2) is greater than 0.125, with increasing SDBS content (n(SDBS)/n(SiO2) = 0.25), the synthesized SAPO-11 contains amorphous materials, which leads to a decline in the ESA; with the further increase in SDBS content (n(SDBS)/n(SiO2) = 0.5), the products are all amorphous materials. These results indicate that in the case of n(SDBS)/n(SiO2) = 0.125, the synthesized SAPO-11 molecular sieve (S–S3) has the most external Brønsted acid centers and the highest ESA of these SAPO-11, and these advantages favor generation of the di-branched isomers in hydrocarbon hydroisomerization. Among these Pt/SAPO-11 catalysts, Pt/S–S3 displays the highest selectivity to entire isomers (83.4%), the highest selectivity to di-branched isomers (28.1%) and the minimum hydrocracking selectivity (15.7%) in n-nonane hydroisomerization.

scholarly journals Layered Materials with Catalytic Applications: Pillared and Delaminated Zeolites from MWW Precursors

2012 ◽  
Vol 2012 ◽  
pp. 1-35 ◽  
Author(s):  
Urbano Díaz
Keyword(s):  
Surface Area ◽  
Molecular Sieves ◽  
Active Sites ◽  
External Surface ◽  
Synthesis Method ◽  
Textural Properties ◽  
Inorganic Materials ◽  
External Surface Area ◽  
Inorganic Supports ◽  
Zeolitic Materials

Delaminated and pillared zeolites are an innovative family of molecular sieves which introduced a different concept inside the synthesis of active catalysts or inorganic supports. These types of materials exhibit an elevated accessibility due to their open structure, characterized by the high external surface area without imposed restrictions controlled by the pore sizes. These open zeolites are conformed by crystalline ordered (pillared zeolites) or disordered (delaminated zeolites) individual layers, exhibiting textural properties which are favorable to carry out catalytic processes in which it is necessary to employ catalysts with completely accessible active sites. The elevated external surface area of these zeolites is profitable to generate more specific organic-inorganic materials, acting in this case as stable inorganic matrixes. The preparation of this open type-zeolites family is based on the modification of, previously synthesized, zeolitic precursors which are preexpanded to obtain the final delaminated or pillared zeolites which exhibit very different physicochemical properties compared with the starting precursors. Along this paper, the most relevant MWW-type high accessible zeolitic materials will be considered. Their nature, characteristics, and reactivity will be shown in the function of the employed synthesis method for their preparation and the postsynthesis treatments carried out, tuning their properties.

scholarly journals The Amounts of Water Adsorbed to the Surface of Clay Minerals at the Plastic Limit

2017 ◽  
Vol 64 (3-4) ◽  
pp. 155-162
Author(s):  
Aleksandra Gorączko ◽  
Andrzej Olchawa
Keyword(s):  
Surface Area ◽  
External Surface ◽  
Solid Phase ◽  
Water System ◽  
Basal Spacing ◽  
Plastic Limit ◽  
X Ray Diffraction ◽  
External Surface Area ◽  
X Ray ◽  
Water Layers

AbstractThe paper presents results of a study on the amount of water associated with the solid phase of the clay water system at the plastic limit. Two model monomineral clays, namely kaolinite, and montmorillonite, were used in the study. The latter was obtained by gravitational sedimentation of Na-bentonite (Wyoming).The calculated mean number of water molecule layers on the external surface of montmorillonite was 14.4, and water in interlayer spaces constituted 0.3 of the water mass at the plastic limit.The number of water layers on the external surface of kaolinite particles was 63, which was related to the higher density of the surface electrical charge of kaolinite compared to that of montmorillonite.The calculations were made on the basis of the external surface area of clays and the basal spacing at the plastic limit measured by an X-ray diffraction test. The external surface area of clays was estimated by measuring sorption at a relative humidity p/p0 = 0.5.

scholarly journals The submicron particles FORMULATION OF IONIC-GELATION SUBMICRON PARTICLES LOADING EXTRACT PAPAYA LEAVES (Carica papaya L.) WITH LACTIC ACID ISOLATES

2019 ◽  
Vol 4 (3) ◽  
pp. 77
Author(s):  
Mardiyanto Mardiyanto ◽  
Budi Untari ◽  
Najma Annuria Fithri ◽  
Sofia Sandi ◽  
Zahrul Mawaddah
Keyword(s):  
Particle Size ◽  
Lactic Acid ◽  
Encapsulation Efficiency ◽  
Carica Papaya ◽  
Ethanolic Extract ◽  
Submicron Particles ◽  
Ionic Gelation ◽  
Particle Characterization ◽  
Submicron Particle ◽  
Optimum Formula

A study regarding ionic-gelation submicron particle of papaya leaves (Carica papaya L.) extract with lactic acid of weeds potentially for antidiarrhea has been conducted. Preparation of papaya leaves ethanolic extract and lactic acid isolate into particles was done by ionic gelation method. This study aimed to determine: the major compound of extract, the total quercertine of extract, the percent value of encapsulation efficiency of the optimum formula which was varied by (CaOH)2 of the three formulas, and physical properties of particles. Formula 1 was using (CaOH)2 of 12.5 gram; formula 2 (CaOH)2 of 17,5 gram; formula 3 (CaOH)2 of 22.5 gram. The results showed formula 1 as the optimum formula that has the highest %EE. The average %EE values ​​of F1; F2; F3 respectively were 80,82%; 80,41%; 80,31%. The results of particle characterization using the PSA in the optimum formula produced particle size values ​​with an average of 253.6 nm, PDI of 0.218, and zeta potential +8 mV respectively.

scholarly journals Plasma Catalysis: Distinguishing between Thermal and Chemical Effects

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 185 ◽  
Author(s):  
Guido Giammaria ◽  
Gerard van Rooij ◽  
Leon Lefferts
Keyword(s):  
Gas Phase ◽  
Surface Area ◽  
Thermal Effects ◽  
External Surface ◽  
Plasma Chemistry ◽  
Internal Surface ◽  
Plasma Power ◽  
External Surface Area ◽  
Internal Surface Area ◽  
Chemical Effects

The goal of this study is to develop a method to distinguish between plasma chemistry and thermal effects in a Dielectric Barrier Discharge nonequilibrium plasma containing a packed bed of porous particles. Decomposition of CaCO3 in Ar plasma is used as a model reaction and CaCO3 samples were prepared with different external surface area, via the particle size, as well as with different internal surface area, via pore morphology. Also, the effect of the CO2 in gas phase on the formation of products during plasma enhanced decomposition is measured. The internal surface area is not exposed to plasma and relates to thermal effect only, whereas both plasma and thermal effects occur at the external surface area. Decomposition rates were in our case found to be influenced by internal surface changes only and thermal decomposition is concluded to dominate. This is further supported by the slow response in the CO2 concentration at a timescale of typically 1 minute upon changes in discharge power. The thermal effect is estimated based on the kinetics of the CaCO3 decomposition, resulting in a temperature increase within 80 °C for plasma power from 0 to 6 W. In contrast, CO2 dissociation to CO and O2 is controlled by plasma chemistry as this reaction is thermodynamically impossible without plasma, in agreement with fast response within a few seconds of the CO concentration when changing plasma power. CO forms exclusively via consecutive dissociation of CO2 in the gas phase and not directly from CaCO3. In ongoing work, this methodology is used to distinguish between thermal effects and plasma–chemical effects in more reactive plasma, containing, e.g., H2.

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