Adsorption of aromatic hydrocarbons in NaX zeolite. 2. Kinetics

Ruthven, Douglas M.; Kaul, Bal K.

doi:10.1021/ie00021a029

Cited by 50 publications

(40 citation statements)

References 3 publications

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“…To correlate the diffusivities with the shape and size of the sorbate molecules proved a surprisingly challenging task [29]. It is evident from Table 2 that the sequence of diffusivities actually follows the sequence of critical molecular diam- Table 2 Diffusion coefficients, pre-exponential factors, activation energies E a and activation entropies S * of aromatics and cyclic hydrocarbons…”

Section: Kinetic Properties At Different Sorption Coveragementioning

confidence: 99%

Sorption of hydrocarbons in silicalite-1 studied by intelligent gravimetry

Ban

Gui

Duan

et al. 2005

Fluid Phase Equilibria

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Section: Kinetic Properties At Different Sorption Coveragementioning

confidence: 99%

Sorption of hydrocarbons in silicalite-1 studied by intelligent gravimetry

Ban

Gui

Duan

et al. 2005

Fluid Phase Equilibria

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“…(21) is a useful relationship to estimate the effect of temperature on the 1,3,5-TIPB transport. Based on the experimental data reported by Ruthven and Kaul (1993) on the diffusivity of 1,3,5 TEB in faujasite zeolite, with a critical diameter of 9Å, ED was estimated at 17 kcal/mole (Ruthven and Kaul, 1993;Karger and Ruthven, 1992). Since 1,3,5-TIPB and 1,3,5-TEB have close critical molecular diameter, it is expected that ED for 1,3,5-TIPB should be in a close range.…”

Section: (Iii)-the Effectiveness Factor Of 135-tipb Catalytic Crackingmentioning

confidence: 99%

Diffusion and catalytic cracking of 1,3,5 tri-iso-propyl-benzene in FCC catalysts

Al-Khattaf

Atias

Jarosch

et al. 2002

Chemical Engineering Science

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The present study describes catalytic cracking experiments developed in a novel CREC Riser Simulator using 1,3,5-Tri-iso-propyl-benzene and two FCC catalysts with different crystal sizes (0.4-μm and 0.9-μm diameter). The experiments are modeled using an unsteady state model for both gas and catalyst phases. It is found that a quasi-steady state approximation can be used for the catalyst and changes in the gas phase can be accounted, under the allowed model simplifications, with a relatively simple unsteady state equation. The model is completed using two catalytic decay models, with one of them involving a decay function based on "reactant converted". Experimental and modeling observations point towards an overall cracking reaction rate controlled by diffusion at 350°C -450°C with this rate shifting to one being controlled by the intrinsic cracking reaction at 500°C -550°C.(*) Author to whom correspondence may be addressed 2 1-IntroductionThe oil refining industry has experienced in recent years, a dramatic increase in the price and availability of crude oil. In this respect, new catalyst technology is needed to process heavier feedstocks and to produce more environmentally friendly products.The currently available 60-μm commercial FCC catalysts are manufactured with 1-2-μm Y-zeolite crystals dispersed in an amorphous silicaalumina matrix . The majority of the active sites are located within the zeolite pore structure. In order for the reaction to proceed, molecules have to diffuse through the large matrix pores into the zeolite crystals.As a result, only certain hydrocarbon species with a kinetic diameter smaller than 10.2 Å can penetrate the zeolite pores (Leiby, 1992). Hence the relationship between catalytic cracking reaction and diffusional processes can determine the extent of cracking and greatly influence the product selectivity. Such phenomena are complex and theoretical models to describe such systems are needed (Bidabehere and Sedran, 2000).Diffusion in catalysts belongs in many cases to the Knudsen regime.However, diffusion in zeolites falls more in a so-called "configurational regime", since the size of the hydrocarbon molecule is nearly the size of the zeolite inner channels (Karger and Ruthven, 1992; Gates et al,1979). As a result, diffusion of the hydrocarbon molecules is governed by an almost continuous interaction between the zeolite crystal and the diffusing molecules (Karger and Ruthven,1992;Gates et al,1979). In addition, there may be compounded effects 3 with larger hydrocarbon molecules hindering the diffusion of smaller molecules.As a result, lighter product molecules may be trapped or delayed in a zeolite pore network already filled with sorbed heavier molecules (Gates et al, 1979). The 1,3,5-TIPB is a relatively bulky molecule with a critical molecular diameter of about 9.5 Å (Bhatai, 1991). Due to its large size, it has been used to simulate the diffusional constrains expected in the catalytic cracking of gas oil (Aguiar et al, 1995). For instance, the cracking of 1,3,5-TIPB ...

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“…These include desulfurization by microbial oxidation 6,7 , chemical oxidation 8,9 , ultraviolet-assisted oxidation 10 , biodesulfurization 11,12 , and adsorption [13][14][15][16][17] . In the adsorption process, sulfur compounds are removed via p-complexation [18][19][20][21][22] .…”

Section: Introductionmentioning

confidence: 99%

ADSORPTION OF 4,6-DIMETHYLDIBENZOTHIOPHENE OVER Cu/ZrO2

Baeza¹,

Bassi²,

Villarroel³

et al. 2015

J. Chil. Chem. Soc.

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The adsorption of refractory sulfur molecule 4,6-Dimethyldibenzothiophene (4,6-DMDBT) over copper supported on zirconia, using different copper loadings (2-10% w/w) and a zirconia support with a high specific surface area, was studied. The results showed that the adsorption capacity of 4,6-DMDBT over Cu/ZrO 2 increased with copper content, reaching a maximum at around 8% Cu (0.58 mmol 4,6-DMDBT per gram of adsorbent). The results of characterizations with H 2 -TPR, Electrophoretic Migration, and XRD demonstrated that this Cu loading (8%) also corresponds to a maximum copper dispersion capacity for ZrO 2 support. Also, these absorbents showed considerable selectivity toward the adsorption of 4,6-DMDBT in a feed stream also containing Quinoline, decreasing adsorption capacity of 4,6-DMDBT by only 35%, despite both molecules being present in the same concentrations. The results of this work showed that desulfurization adsorption using Cu/ZrO 2 adsorbents can be an effective method to remove this type of refractory sulfur molecules, and an excellent alternative as a complementary process for deep desulfurization in the fuel industry.

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Adsorption of aromatic hydrocarbons in NaX zeolite. 2. Kinetics

Cited by 50 publications

References 3 publications

Sorption of hydrocarbons in silicalite-1 studied by intelligent gravimetry

Sorption of hydrocarbons in silicalite-1 studied by intelligent gravimetry

Diffusion and catalytic cracking of 1,3,5 tri-iso-propyl-benzene in FCC catalysts

ADSORPTION OF 4,6-DIMETHYLDIBENZOTHIOPHENE OVER Cu/ZrO2

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