Development, Implementation And Validation Of In-Situ Raman Hot Stage Reactor Open Access
- Other title
In-Situ Raman spectroscopy
Principal component analysis
On-line Chemical Sensor
Hot Stage Reactor
- Type of item
- Degree grantor
University of Alberta
- Author or creator
Khalili, Khaled NM
- Supervisor and department
McCaffrey,William ( Chemical & Material Engineering)
- Examining committee member and department
Semagina, Natalia ( Chemical & Material Engineering)
Kuznicki, Steven ( Chemical & Material Engineering)
Prasad, Vinay ( Chemical & Material Engineering)
Department of Chemical and Materials Engineering
- Date accepted
- Graduation date
Master of Science
- Degree level
In the upgrading of heavy feeds, it is essential to avoid the onset formation of mesophase, which is considered a precursor for coke formation. The formation of this aromatic dense phase leads to serious problems such as catalyst deactivation, limiting the vacuum residue conversion, and fouling in the reactors and the downstream equipment; subsequently, a costly mechanical removal will be necessary to remove the coke. Therefore, tracking of the mesophase formation at in-situ conditions is important step towards avoiding the onset formation of carbonaceous mesophase.
In this work, a fiber-coupled in-situ Raman hot reactor was designed, constructed and validated. The system has been developed as on-line chemical sensor to track evolution of the two graphitization Raman bands associated with the mesophase formation, namely the 1575cm-1 band and the band located near 1340cm-1. The operation of the system is based on acquiring real-time backscattered Raman spectra from a hot stage reactor running at high temperature and sometimes high-pressure conditions.
The outcome of this system has been validated using non-reactive and reactive systems. In terms of non-reactive systems, the spectra of some common solvents such as toluene and 1-methylnapthalene have been acquired using this system and then compared with the published spectra; excellent spectral matching in the range of ± 5cm-1 is observed. On the other hand, the hydro-desulfurization reaction of benzothiophene using 1-methylnapthalene as a solvent has been used as a model reaction for system validation. This reaction has been conducted ex-situ and in-situ at the same experimental conditions i.e. 290° C and 2.5 MPa of hydrogen pressure. The GC/MS analysis of the ex-situ shows hydrodesulphurization of benzothiophene and formation of ethylbenzene, which is in agreement with the well-known chemistry of this reaction; in addition, a considerable hydrogenation of the solvent was observed in the products of the ex-situ runs, which confirms the hydrogenation capability of the used catalyst. The spectral data, which have been acquired during the in-situ runs, have been preprocessed using the airPLS algorithm to remove the fluorescence background from the spectra that have been then analyzed using multivariate PCA analysis. The PCA analysis confirms the evolution of the Raman bands associated with ethylbenze formation and the decline of the Raman bands attributed to benzothiophen; moreover, the PCA analysis also shows a concomitant decrease of the aromatic content of the mixture via hydrogenation of aromatic rings which confirms the hydrogenation of the solvent that have been observed in the ex-situ runs.
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