In-Situ Characterization OF 1-Hexene Concentration with a Helium-Neon Laser in the presence of a Solid Catalyst

Keywords: HeNe laser, in-situ measurements, 1-hexene, heterogeneous catalyst, Computational Fluid Dynamics


This study provides evidence that a helium-neon (He-Ne) laser operating in the Mid-infrared (MIR) at a wavelength of 3.39 μm can detect variations in 1-hexene concentration in the presence of a solid catalyst. The in-situ and online characterization of the concentration of 1-hexene, as an example of a hydrocarbon, is relevant to enhance the current understanding of the interaction between hydrodynamics and chemistry in different heterogeneous catalytic processes. We designed and built a laboratory-scale downer unit that enabled us to analyze heterogeneous catalytic reactions and provided optical access. The lab-scale reactor was 180-cm long, had an internal diameter of 1.3 cm, and was made of fused quartz to allow the passage of the laser beam. 1-hexene was carefully measured, vaporized, and fed into the reactor through two inlets located at an angle of 45 degrees from the vertical descendent flow and 70 cm below the input of a solid catalyst and a purge flow entraining N2. A system of five heaters, which can be moved in the vertical direction to allow the passage of the laser beam, guaranteed temperatures up to 823 K. Computational Fluid Dynamics (CFD) simulations of the hydrodynamics of the system indicated that a uniform temperature profile in the reaction section was reached after the catalyst and the feed mixed. The estimated catalyst to oil ratio and time on stream in the experiments were, respectively, 0.4 to 1.3 and 2 s. After a correction for laser power drift, the experimental results showed a linear response of the fractional transmission to the 1-hexene concentration that was independent of temperature in the 373 K–673 K range. Even in the presence of a catalyst, the absorption of 1-hexene at the MIR frequency of the laser was high enough to enable the detection of 1-hexene since the fractional absorption of the absorbing path length in these experiments was close to zero (0.013 m) and the 1-hexene concentrations were higher than 1.254 × 10-5 mol/cm3. This result demonstrated the ability of the laser system to measure the concentration of 1-hexene in the presence of a catalyst and indicates that it can be used to better decouple hydrodynamics from kinetics in heterogeneous catalytic processes.

Author Biographies

Juan Guillermo Lacayo, Universidad Nacional de Colombia, Colombia

MSc en Ingeniería Química, Grupo de investigación Bioprocesos y Flujos reactivos, Facultad de Minas, Universidad Nacional de Colombia, Medellín- Colombia,

Sebastian López, Universidad Nacional de Colombia, Colombia

MSc en Ingeniería Química. Grupo de investigación Bioprocesos y Flujos reactivos, Facultad de Minas, Universidad Nacional de Colombia, Medellín- Colombia,

David Soto , Universidad Nacional de Colombia, Colombia

MSc en Ingeniería Química, Grupo de investigación Bioprocesos y Flujos reactivos, Facultad de Minas, Universidad Nacional de Colombia, Medellín- Colombia,

Alejandro Molina*, Universidad Nacional de Colombia, Colombia

PhD. en Ingeniería Grupo de investigación Bioprocesos y Flujos reactivos, Facultad de Minas, Universidad Nacional de Colombia Medellín-Colombia,


H. Lasa and D. Kraemer, “Novel Techniques for FCC Catalyst Selection and Kinetic Modelling,” in Chemical Reactor Technology for Environmentally Safe Reactors and Products, Dordrecht: Springer Netherlands, 1992, pp. 71–131.

C. I. C. Pinheiro et al., “Fluid Catalytic Cracking (FCC) Process Modeling, Simulation, and Control,” Ind. Eng. Chem. Res., vol. 51, no. 1, pp. 1–29, Nov. 2011.

R. Sadeghbeigi, Fluid catalytic cracking handbook: An expert guide to the practical operation, design, and optimization of FCC units. Oxford, UK: Elsevier, 2012. Available:

H. Copete-López and S. Sánchez-Acevedo, “An Approach to Optimal Control of the Combustion System in a Reverberatory Furnace,” TecnoLógicas, no. 23, pp. 13–29, Dec. 2009.

R. Ríos, C. A. Ramos-Paja, and J. J. Espinosa, “A control system for reducing the hydrogen consumption of PEM fuel cells under parametric uncertainties,” TecnoLógicas, vol. 19, no. 37, pp. 45–59, Jun. 2016.

I. D. Ramírez-Rivas, “Anaerobic digestion modeling: from one to several bacterial populations,” TecnoLógicas, no. 31, pp. 181–201, Nov. 2013.

J. C. Briñez-De León, A. Restrepo-Martínez, and F. López-Giraldo, “Pixels Intensity Evolution to Describe the Plastic Films Deformation,” TecnoLógicas, SE-Computer science, pp. 695–707, Nov. 2013.

E. Reyes-Vera, D. E. Senior, J. M. Luna-Rivera, and F. E. López-Giraldo, “Advances in electromagnetic applications and communications,” TecnoLógicas, vol. 21, no. 43, pp. 9–13, Sep. 2018.

V. H. Aristizabal, “Introducción a la Tecnología de Fibras Ópticas y Análisis numérico de la propagación de la luz en fibras micro-estructuradas” TecnoLógicas, no. 19, pp. 141–166, Dec. 2007.

G. J. De Castilho and M. A. Cremasco, “Comparison of downer and riser flows in a circulating bed by means of optical fiber probe signals measurements” Procedia Eng., vol. 42, pp. 295–302, 2012.

A. Lanza, M. Islam, and H. De Lasa, “Particle cluster sizing in downer units. Applicable methodology across downer scale units,” Powder Technol., vol. 316, pp. 198–206, Jul. 2017.

J. Liu, J. R. Grace, and X. Bi, “Novel multifunctional optical-fiber probe: I. Development and validation,” AIChE Journal., vol. 49, no. 6, pp. 1405–1420, Jun. 2003.

R. J. Santoro and C. R. Shaddix, “Laser Induced Incandescence,” in Applied Combustion Diagnostics, New York: Taylor & Francis, 2002, pp. 252–286. Available:

A. B. S. Alquaity, E. Es-sebbar, and A. Farooq, “Sensitive and ultra-fast species detection using pulsed cavity ringdown spectroscopy,” Opt. Express, vol. 23, no. 6, pp. 7217–7226, Mar. 2015.

R. K. Hanson, R. M. Spearrin, and C. S. Goldenstein, Spectroscopy and Optical Diagnostics for Gases. Springer International Publishing, 2016.

E. F. Nasir and A. Farooq, “Intra-pulse laser absorption sensor with cavity enhancement for oxidation experiments in a rapid compression machine,” Opt. Express, vol. 26, no. 11, pp. 14601–14609, May. 2018.

S. Lopez-Zamora, A. Alkhlel, and H. De Lasa, “Monitoring the progress of catalytic cracking for model compounds in the mid-infrared (MIR) 3200--2800 Cm-1 range,” Chem. Eng. Sci., vol. 192, pp. 788–802, Dec. 2018.

H. De Lasa, “Riser simulator.” Google Patents, 1992.

M. P. Helmsing, M. Makkee, and J. A. Moulijn, “Development of a bench scale FCC microriser,” Deactivation and Testing of Hydrocarbon-Processing Catalysts Chapter 24, pp 322-339, 1996.

X. Dupain, E. D. Gamas, R. Madon, C. P. Kelkar, M. Makkee, and J. A. Moulijn, “Aromatic gas oil cracking under realistic FCC conditions in a microriser reactor,” Fuel, vol. 82, no. 13, pp. 1559–1569, Sep. 2003.

M. A. Den Hollander, M. Wissink, M. Makkee, and J. A. Moulijn, “Gasoline conversion: reactivity towards cracking with equilibrated FCC and ZSM-5 catalysts,” Appl. Catal. A Gen., vol. 223, no. 1–2, pp. 85–102, Jan. 2002.

A. Corma, C. Martínez, F. V Melo, L. Sauvanaud, and J. Y. Carriat, “A new continuous laboratory reactor for the study of catalytic cracking,” Appl. Catal. A Gen., vol. 232, no. 1–2, pp. 247–263, Jun. 2002.

A. Corma and L. Sauvanaud, “FCC testing at bench scale: New units, new processes, new feeds,” Catal. today, vol. 218-219, pp. 107–114, Dec. 2013.

ASTM D3907 / D3907M-19, Standard Test Method for Testing Fluid Catalytic Cracking (FCC) Catalysts by Microactivity Test, ASTM International, West Conshohocken, PA, 2019.

P. O’Connor and M. B. Hartkamp, “A microscale simulation test for Fluid Catalytic Cracking.,” Characterization and Catalyst Development., Chapter 13 pp 135-147, 1989.

T. Myrstad and H. Engan, “Testing of resid FCC catalysts in MAT,” Appl. Catal. A Gen., vol. 171, no. 1, pp. 161–165, Jun. 1998.

C. Delattre, M. Forissier, I. Pitault, D. Schweich, and J. R. Bernard, “Improvement of the microactivity test for kinetic and deactivation studies involved in catalytic cracking,” Chem. Eng. Sci., vol. 56, no. 4, pp. 1337–1345, Feb. 2001.

D. Wallenstein, M. Seese, and X. Zhao, “A novel selectivity test for the evaluation of FCC catalysts,” Appl. Catal. A Gen., vol. 231, no. 1–2, pp. 227–242, May. 2002.

M. A. Den Hollander, M. Makkee, and J. A. Moulijn, “Coke formation in fluid catalytic cracking studied with the microriser,” Catal. today, vol. 46, no. 1, pp. 27–35, Nov. 1998.

M. T. Shah, R. P. Utikar, V. K. Pareek, G. M. Evans, and J. B. Joshi, “Computational fluid dynamic modelling of FCC riser: A review,” Chem. Eng. Res. Des., vol. 111, pp. 403–448, Jul. 2016.

Y. N. Kim, C. Wu, and Y. Cheng, “CFD simulation of hydrodynamics of gas--solid multiphase flow in downer reactors: revisited,” Chem. Eng. Sci., vol. 66, no. 21, pp. 5357–5365, Nov. 2011.

G. C. Lopes, L. M. Rosa, M. Mori, J. R. Nunhez, and W. P. Martignoni, “Three-dimensional modeling of fluid catalytic cracking industrial riser flow and reactions,” Comput. Chem. Eng., vol. 35, no. 11, pp. 2159–2168, Nov. 2011.

M. A. Ospina-Alarcón, A. B. Barientos-Ríos, M. O. Bustamante-Rua “Influence of the pulse wave in the stratification of high density particles in a JIG device,” TecnoLógicas, vol. 19, no. 36, pp. 13–25, Jan. 2016.

N. Gomez and A. Molina, “Analysis of the Particle Clustering Phenomenon in the Fluid Catalytic Cracking of Gasoil in a Downer Reactor,” Chem. Eng. Technol., vol. 42, no. 6, pp. 1293–1303, Apr. 2019.

S. Al-Khattaf, J. A. Atias, K. Jarosch, and H. De Lasa, “Diffusion and catalytic cracking of 1, 3, 5 tri-iso-propyl-benzene in FCC catalysts,” Chem. Eng. Sci., vol. 57, no. 22–23, pp. 4909–4920, Nov. 2002.

Aspen Plus, “Aspen Plus user guide,” Aspen Technol. Limited, Cambridge, USA, 2003. Available:

Ansys Fluent ANSYS inc, “15.0 Theory Guide.” (s/f). Available:

J. A. Souza, J. V. C. Vargas, J. C. Ordonez, W. P. Martignoni, and O. F. von Meien, “Thermodynamic optimization of fluidized catalytic cracking (FCC) units,” Int. J. Heat Mass Transf., vol. 54, no. 5–6, pp. 1187–1197, Feb. 2011.

K. Ropelato, H. F. Meier, and M. A. Cremasco, “CFD study of gas - solid behavior in downer reactors: an Eulerian -Eulerian approach,” Powder Technol., vol. 154, no. 2–3, pp. 179–184, Jul. 2005.

A. Lanza and H. de Lasa, “Scaling-up down flow reactors. CPFD simulations and model validation,” Comput. Chem. Eng., vol. 101, pp. 226–242, Jun. 2017.

V. A. Petrov and V. Y. Reznik, “Measurement of the emissivity of quartz glass,” High Temp.-High Press., vol. 4, no. 6, pp. 687–693, 1972. Available:

S. A. Morsi and A. J. Alexander, “An investigation of particle trajectories in two-phase flow systems,” J. Fluid Mech., vol. 55, no. 2, pp. 193–208, Sep. 1972.

V. Ranade, Computational flow modeling for chemical reactor engineering, vol. 5. San Diego, USA: Academic Press, 2001. Available:

D. F. Swinehart, “The beer-lambert law,” J. Chem. Educ., vol. 39, no. 7, pp. 333. Jul. 1962.

A. E. Klingbeil, “Mid-IR laser absorption diagnostics for hydrocarbon vapor sensing in harsh environments,” (PhD Thesis), Stanford University, Stanford, USA, 2007. Available:

D. A. Skoog, D. M. West, F. James Holler, and S. R. crouch: Fundamentals of analytical chemistry. USA: Nelson Education, 2013.

How to Cite
Lacayo, J. G., López, S., Soto , D., & Molina, A. (2020). In-Situ Characterization OF 1-Hexene Concentration with a Helium-Neon Laser in the presence of a Solid Catalyst. TecnoLógicas, 23(48), 233-248.


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