Rate Parameter Distributions for Isobutane Dehydrogenation and Isobutene Dimerization and Desorption over HZSM-5

Brown, Thomas J.; Miron, David J.; Alanazi, Abdullah K.; Minh, Cam Le

doi:10.3390/catal3040922

Cited by 3 publications

(5 citation statements)

References 32 publications

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“…PERSPECTIVE ON POTENTIAL ZEOLITE TOPOLOGIES FOR DIMERIZATION Dimerization of isobutylene to isooctene over various zeolites as catalysts was previously reported by several researchers as presented in Table 5 and Table S4. Brown et al 227 studied dimerization of isobutylene using wavelet shrinkage denoising combined with time-varying flexible least-squares over ZSM-5 zeolite with Si/Al in the range of 16 to 17 in a reactor at 100 °C for 2 h. The activation energy of dimerization of isobutylene was 48.3 kJ/mol to 267 kJ/mol with an average activation energy of 112 kJ/mol. 227 Koskinen et al 228 reported isooctene synthesis using CO 2 and propane as solvents in reaction medium over ZSM-5 and ZSM-23 zeolites as catalysts at 100 °C and 49−89 atm for 120−200 h. The ZSM-5 catalyst with a Si/Al ratio of 23.8 had a total acidity of 380 μmol/g and the ZSM-23 catalyst with a Si/ Al ratio of 19.7 had a total acidity of 690 μmol/g.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

“…Dimerization of isobutylene to isooctene over various zeolites as catalysts was previously reported by several researchers as presented in Table and Table S4. Brown et al . studied dimerization of isobutylene using wavelet shrinkage denoising combined with time-varying flexible least-squares over ZSM-5 zeolite with Si/Al in the range of 16 to 17 in a reactor at 100 °C for 2 h. The activation energy of dimerization of isobutylene was 48.3 kJ/mol to 267 kJ/mol with an average activation energy of 112 kJ/mol …”

Section: Perspective On Potential Zeolite Topologies For Dimerizationmentioning

confidence: 99%

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Conversion of Isobutylene to Octane-Booster Compounds after Methyl tert-Butyl Ether Phaseout: The Role of Heterogeneous Catalysis

Mahdi

Muraza

2016

Ind. Eng. Chem. Res.

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Over the last decades, the global demand of the production of methyl tert-butyl ether (MTBE) was significantly decreased from 30 million tons per year (MTPY) in 1995 to 12 million tons per year (MTPY) in 2011 because of the phaseout of MTBE in the United States and other countries. MTBE was banned in some countries because it produces health and environmental pollution and contaminates water and air quality. After MTBE phaseout, isobutylene feedstock is used for the production of another octane booster compound such as isooctane with a more environmental-friendly reputation. Isooctane is obtained by dimerization, trimerization, and oligomerization of isobutylene followed by a hydrogenation step. Dimerization of isobutylene to isooctane is a simple and low-cost-effective technology using heterogeneous catalysts such as zeolites, metal oxides, and resins. Zeolites are potential catalyst with high selectivity, high stability, easy regeneration, and low-cost production. The conversion and selectivity can be increased with higher acid strength, a larger dimensional channel, and higher pore size. USY zeolite (FAU topology) is a promising zeolite framework to be improved in the dimerization of isobutylene. Further improvement of USY zeolite has been emphasized as needed to develop better dimerization catalysts.

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Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Section: Perspective On Potential Zeolite Topologies For Dimerizationmentioning

confidence: 99%

Conversion of Isobutylene to Octane-Booster Compounds after Methyl tert-Butyl Ether Phaseout: The Role of Heterogeneous Catalysis

Mahdi

Muraza

2016

Ind. Eng. Chem. Res.

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“…The pressure-varying parameters, n ∞, P and K P , in eq are determined using methodology developed by Kalaba and Tesfatsion, called flexible least squares for time-varying linear regression (FLS-PVLR, for the analogous pressure-varying regression) and have been applied to time-varying parameters for econometric processes as well as rate constants for gas–solid reactions. − For all of these processes, modeled parameters evolve slowly and smoothly over time. For isothermal adsorption, the parameters are assumed to vary slowly and smoothly with increasing pressure.…”

Section: Introductionmentioning

confidence: 99%

Adsorption Properties from Pressure-Varying Langmuir Parameters: n-Butane and Isobutane on Activated Carbon

Brown

2016

Energy Fuels

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Isothermal adsorption data for n-butane and isobutane on BAX 1500 activated carbon reported by Whittaker et al. [Predicting the Integral Heat of Adsorption for Gas Physisorption on Microporous and Mesoporous AdsorbentsWhittakerP. B.WangX.ZimmermannW.Regenauer-LiebK.ChuaH. T. Whittaker, P. B. Wang, X. Zimmermann, W. Regenauer-Lieb, K. Chua, H. T. 10.1021/jp410873vJ. Phys. Chem. C201411883508358] were modeled with pressure-varying Langmuir adsorption parameters using flexible least squares for pressure-varying linear regression. Coverage varies with pressure and at distinct transitions; when the ratio of uptake to capacity is 0.69 ± 0.04, monolayer coverage is achieved or micropore volume is filled. Monolayer transitions are observed for the 298, 323, and 348 K isotherms, while micropore volume transitions are only apparent for the 298 K isotherms. The resultant adsorbent surface area is 1335 ± 25 cm2 g–1, and the micropore volume is 0.48 ± 0.03 cm3 g–1. Molecular areas, corresponding to excluded adsorbate areas, are dependent upon the temperature and range from 29.1 to 31.1 Å2 for n-butane and from 31.8 to 32.7 Å2 for isobutane for the 298–348 K isotherms. Average molecular areas, calculated from monolayer capacities, are 20.5 ± 0.4 Å2 for n-butane and 21.9 ± 0.7 Å2 for isobutane and correspond to minimum areas, excluding surface mobility and packing. Molecular volumes, calculated from micropore volume capacities, are 45 ± 2 Å3 for n-butane and 58 ± 2 Å3 for isobutane and are comparable to molecular volumes determined from Lennard–Jones 12:6 potentials. Entropies of adsorption increase from −1.06 ± 0.04 kJ K–1 kg–1 at 298 K to −0.671 ± 0.008 kJ K–1 kg–1 at 348 K for n-butane and from −0.948 ± 0.018 kJ K–1 kg–1 at 298 K to −0.682 ± 0.010 kJ K–1 kg–1 at 348 K for isobutane and indicate increased mobility at monolayer coverage.

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“…Rate coefficients for selective oxidation can be simplified to Equation (12) where the rate coefficient ratio of activated complex to surface diffusion away from active sites control the temperature-dependence [21].…”

Section: Calculating Time-and Temperature-varying Activation Energiesmentioning

confidence: 99%

“…This compensation effect highlights the challenge in determining the true activation energies and prefactors. Rate coefficients for selective oxidation can be simplified to Equation (12) where the rate coefficient ratio of activated complex to surface diffusion away from active sites control the temperature-dependence [21].…”

Section: High-temperature Average Rate-parameters For Methacrolein Fmentioning

confidence: 99%

Time- and Temperature-Varying Activation Energies: Isobutane Selective Oxidation to Methacrolein over Phosphomolybdic Acid and Copper(II) Phosphomolybdates

et al. 2016

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Abstract:The selective oxidation energetics of isobutane to methacrolein over phosphomolybdic acid and copper(II) phosphomolybdates have been investigated using low-pressure, pseudo-steady-state and temperature-programming techniques. Time-varying flexible least squares methods were used to determine variations in oxidation activation energies as the temperature increases at 5 • C·min −1 . Catalyst activity stabilizes by the fourth consecutive temperature-programmed run. Rate parameters increase linearly with temperature in two sinusoidal, oscillating wave packets. For H 3 PMo 12 O 40 , three distinct reaction pathways are apparent in the fourth run with activation energies 76 ± 3, 93 ± 7 and 130 ± 3 kJ·mol −1 , and under these experimental conditions are observed at the optimum temperatures 704 ± 7 K, 667 ± 25 K and 745 ± 7 K, respectively. Over the copper-containing catalysts, two pathways are apparent: 76 ± 3 kJ·mol −1 at 665 ± 9 K and 130 ± 3 kJ·mol −1 at 706 ± 9 K. The three activation energies indicate either different reaction pathways leading to methacrolein or distinct active sites on the catalyst surface. The intermediate activation energy, 93 kJ·mol −1 , only observed over phosphomolybdic acid, may be linked to hydrogen bonding. Differences in optimum temperatures for the same activation energies for H 3 PMO 12 O 40 and for the copper catalysts indicate that compensating entropy changes are smaller over H 3 PMo 12 O 40 . The inclusion of copper enhances catalyst stability and activity.

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Rate Parameter Distributions for Isobutane Dehydrogenation and Isobutene Dimerization and Desorption over HZSM-5

Cited by 3 publications

References 32 publications

Conversion of Isobutylene to Octane-Booster Compounds after Methyl tert-Butyl Ether Phaseout: The Role of Heterogeneous Catalysis

Conversion of Isobutylene to Octane-Booster Compounds after Methyl tert-Butyl Ether Phaseout: The Role of Heterogeneous Catalysis

Adsorption Properties from Pressure-Varying Langmuir Parameters: n-Butane and Isobutane on Activated Carbon

Time- and Temperature-Varying Activation Energies: Isobutane Selective Oxidation to Methacrolein over Phosphomolybdic Acid and Copper(II) Phosphomolybdates

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