Non-isothermal reduction of silica-supported nickel catalyst precursors in hydrogen atmosphere: a kinetic study and statistical interpretation
Abstract
A series of silica-supported nickel catalyst precursors was synthesized with different SiO2/Ni mole ratios (0.20, 0.80 and 1.15). Non-isothermal reduction of Ni catalyst precursors was investigated by temperature-programmed reduction at four different heating rates (2, 5, 10 and 20 A degrees C min(-1)), in a hydrogen atmosphere. Kinetic parameters (E (a), A) were determined using Friedman isoconversional method. It was found that for all mole ratios, apparent activation energy is practically constant in conversion range of alpha = 30-70 %. In considered conversion range, the following values of apparent activation energy were found: E (a) = 129.5 kJ mol(-1) (SiO2/Ni = 0.20), E (a) = 133.8 kJ mol(-1) (SiO2/Ni = 0.80) and E (a) = 125.0 kJ mol(-1) (SiO2/Ni = 1.15). Using two special functions (y(alpha) and z(alpha)), the kinetic model was determined. It was established that reduction of Ni catalyst precursors with different SiO2/Ni mole ratios is a complex process and can be described by ...two-parameter estak-Berggren (SB) autocatalytic model. Based on established values of SB parameters for each mole ratio, the possible mechanism was discussed. It was found that for all investigated ratios, the Weibull distribution function fits very well the experimental data, in the wide range of conversions (alpha = 5-95 %). Based on obtained values of Weibull shape parameter (theta), it was found that experimentally evaluated density distribution functions of the apparent activation energies can be approximated by the unbalanced peaked normal distribution.
Keywords:
Temperature-programmed reduction (TPR) / SiO2/Ni catalysts / Kinetics / Sestak-Berggren autocatalytic model / IPPC functionSource:
Journal of the Iranian Chemical Society, 2014, 11, 6, 1743-1758Publisher:
- Springer, New York
Funding / projects:
- Dynamics of nonlinear physicochemical and biochemical systems with modeling and predicting of their behavior under nonequilibrium conditions (RS-MESTD-Basic Research (BR or ON)-172015)
- Nanostructured Functional and Composite Materials in Catalytic and Sorption Processes (RS-MESTD-Integrated and Interdisciplinary Research (IIR or III)-45001)
DOI: 10.1007/s13738-014-0447-1
ISSN: 1735-207X
WoS: 000344082600027
Scopus: 2-s2.0-84910598392
Collections
Institution/Community
IHTMTY - JOUR AU - Jankovic, Bojan AU - Čupić, Željko AU - Jovanović, Dušan M. PY - 2014 UR - https://cer.ihtm.bg.ac.rs/handle/123456789/1405 AB - A series of silica-supported nickel catalyst precursors was synthesized with different SiO2/Ni mole ratios (0.20, 0.80 and 1.15). Non-isothermal reduction of Ni catalyst precursors was investigated by temperature-programmed reduction at four different heating rates (2, 5, 10 and 20 A degrees C min(-1)), in a hydrogen atmosphere. Kinetic parameters (E (a), A) were determined using Friedman isoconversional method. It was found that for all mole ratios, apparent activation energy is practically constant in conversion range of alpha = 30-70 %. In considered conversion range, the following values of apparent activation energy were found: E (a) = 129.5 kJ mol(-1) (SiO2/Ni = 0.20), E (a) = 133.8 kJ mol(-1) (SiO2/Ni = 0.80) and E (a) = 125.0 kJ mol(-1) (SiO2/Ni = 1.15). Using two special functions (y(alpha) and z(alpha)), the kinetic model was determined. It was established that reduction of Ni catalyst precursors with different SiO2/Ni mole ratios is a complex process and can be described by two-parameter estak-Berggren (SB) autocatalytic model. Based on established values of SB parameters for each mole ratio, the possible mechanism was discussed. It was found that for all investigated ratios, the Weibull distribution function fits very well the experimental data, in the wide range of conversions (alpha = 5-95 %). Based on obtained values of Weibull shape parameter (theta), it was found that experimentally evaluated density distribution functions of the apparent activation energies can be approximated by the unbalanced peaked normal distribution. PB - Springer, New York T2 - Journal of the Iranian Chemical Society T1 - Non-isothermal reduction of silica-supported nickel catalyst precursors in hydrogen atmosphere: a kinetic study and statistical interpretation VL - 11 IS - 6 SP - 1743 EP - 1758 DO - 10.1007/s13738-014-0447-1 ER -
@article{ author = "Jankovic, Bojan and Čupić, Željko and Jovanović, Dušan M.", year = "2014", abstract = "A series of silica-supported nickel catalyst precursors was synthesized with different SiO2/Ni mole ratios (0.20, 0.80 and 1.15). Non-isothermal reduction of Ni catalyst precursors was investigated by temperature-programmed reduction at four different heating rates (2, 5, 10 and 20 A degrees C min(-1)), in a hydrogen atmosphere. Kinetic parameters (E (a), A) were determined using Friedman isoconversional method. It was found that for all mole ratios, apparent activation energy is practically constant in conversion range of alpha = 30-70 %. In considered conversion range, the following values of apparent activation energy were found: E (a) = 129.5 kJ mol(-1) (SiO2/Ni = 0.20), E (a) = 133.8 kJ mol(-1) (SiO2/Ni = 0.80) and E (a) = 125.0 kJ mol(-1) (SiO2/Ni = 1.15). Using two special functions (y(alpha) and z(alpha)), the kinetic model was determined. It was established that reduction of Ni catalyst precursors with different SiO2/Ni mole ratios is a complex process and can be described by two-parameter estak-Berggren (SB) autocatalytic model. Based on established values of SB parameters for each mole ratio, the possible mechanism was discussed. It was found that for all investigated ratios, the Weibull distribution function fits very well the experimental data, in the wide range of conversions (alpha = 5-95 %). Based on obtained values of Weibull shape parameter (theta), it was found that experimentally evaluated density distribution functions of the apparent activation energies can be approximated by the unbalanced peaked normal distribution.", publisher = "Springer, New York", journal = "Journal of the Iranian Chemical Society", title = "Non-isothermal reduction of silica-supported nickel catalyst precursors in hydrogen atmosphere: a kinetic study and statistical interpretation", volume = "11", number = "6", pages = "1743-1758", doi = "10.1007/s13738-014-0447-1" }
Jankovic, B., Čupić, Ž.,& Jovanović, D. M.. (2014). Non-isothermal reduction of silica-supported nickel catalyst precursors in hydrogen atmosphere: a kinetic study and statistical interpretation. in Journal of the Iranian Chemical Society Springer, New York., 11(6), 1743-1758. https://doi.org/10.1007/s13738-014-0447-1
Jankovic B, Čupić Ž, Jovanović DM. Non-isothermal reduction of silica-supported nickel catalyst precursors in hydrogen atmosphere: a kinetic study and statistical interpretation. in Journal of the Iranian Chemical Society. 2014;11(6):1743-1758. doi:10.1007/s13738-014-0447-1 .
Jankovic, Bojan, Čupić, Željko, Jovanović, Dušan M., "Non-isothermal reduction of silica-supported nickel catalyst precursors in hydrogen atmosphere: a kinetic study and statistical interpretation" in Journal of the Iranian Chemical Society, 11, no. 6 (2014):1743-1758, https://doi.org/10.1007/s13738-014-0447-1 . .