Novel nitrogen containing heterogeneous catalysts for oxidative dehydrogenation of light paraffins
Introduction
Oxidative dehydrogenation of light alkanes to olefins provides a viable alternative to commercial processes of catalytic dehydrogenation and steam cracking. There are no chemical equilibrium limitations as in dehydrogenation processes and it does not require high temperature and high heat fluxes needed in steam cracking. Reported studies with different catalysts did not achieve yield of olefins from propane above 30 wt% [1], [2], [3], [4], [5], [6], [7]. Only high temperature thermal conversion of paraffins yielded about 35% of olefins [8]. Recent results obtained in oxidative dehydrogenation of n-butane on alumina supported cobalt oxide catalyst indicate efficiency of these catalytic systems for production of ethylene and propylene. Low temperature performance of catalysts in oxidative cracking on n-butane at 550 °C yielded 23% of olefins C2–C3 at 30 wt% total yield of olefins [9]. Enhanced cracking activity was explained by the increase of mobile oxygen share in active species [9] that is a key factor in oxidation processes. Therefore improvement of cobalt catalyst performance requires a further promotion of mobile oxygen share.
Cobalt porphyrins and phthalocyanines have been used as precursors for preparation of carbon supported cobalt catalysts that displayed high activity in reduction of molecular oxygen at low temperature in fuel cells [10], [11]. These samples were prepared by deposition of cobalt phthalocyanine on active carbon followed by heat treatment at 650–700 °C in an inert atmosphere forming Co–N structure.
The object of the present study was the preparation, characterization and testing of a novel cobalt catalyst for oxidative dehydrogenation of light paraffins.
Section snippets
Experimental and methods
Catalytic performance of catalysts was studied in the experimental rig consisting of a stainless tubular preheater and reactor in series, 17 mm ID and 250 mm long with 5.5 mm axial thermowell. Electric tapes controlled by Eurotherm heated the reactor and preheater. 1–4 g catalyst (extrudates 1.5 mm in diameter and 2–3 mm length) diluted with 4–12 g of inert SiC pellets to keep the reactor isothermal, was located between two layers of SiC particles of 3–4 mm in diameter. Total layer of catalyst
Results and discussion
Experimental results depicted in the Table 2 indicate that nitrogen promoted catalysts 1 and 2 were significantly more active in oxidative dehydrogenation of propane and n-butane than non-promoted catalyst 3. Even at 400 °C, the conversion of propane was 24 mol% at 59 wt% of selectivity to olefins (sample 2). Increasing the temperature to 550 °C yielded 33 wt% olefins, significantly higher than yield on non-promoted catalyst 3. Similar results were obtained for n-butane (samples 1–3).
References (15)
- et al.
J. Catal.
(1987) - et al.
Studies in Surface Science and Catalysis
(1992) - et al.
J. Catal.
(1995) - et al.
Catal. Today
(2000) - et al.
Appl. Catal. A
(1999) - et al.
Studies in Surface Science and Catalysis
(1997) Electrochim. Acta
(1986)
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Catalytic cracking of hydrocarbons over modified ZSM-5 zeolites to produce light olefins: A review
2011, Applied Catalysis A: GeneralCitation Excerpt :Propane dehydrogenation (PDH) is an industrialized process for the production of propylene [30] that employs different types of catalysts, e.g., Platinum–tin-based (Pt–Sn) promoters supported on alumina [100,101], silica, ZSM-5 [102–105], SAPO-34 [106,107], etc. The oxidative dehydrogenation (ODH) of ethane and propane over different types of catalysts including modified zeolites such as Ga2O3/HZSM-5 [108], ZnO/HZSM-5 [109], etc., is another route for light olefin production that has been widely studied [110–116]. The mentioned processes are out of the scope in the current paper.
Oxidative dehydrogenation of ethane and propane: How far from commercial implementation?
2007, Catalysis TodayCitation Excerpt :Examples include the production of synthesis gas and ethylene or ethyne for hydroformylation to 1-propanol or butanediol, respectively, or the co-production of propylene or propyne with synthesis gas followed by production of 1-butanol or methylmetacrylate. With non-redox-type catalysts the formation of olefins also occurs by heterogeneously initiated homogeneous reactions under more conventional conditions, i.e., with residence times higher than 0.1 s and temperatures in the 600–750 °C range [285–287,390–394]. Catalysts described are based on Li/Dy/Cl-MgO [184,285,286,390,393] (best ethylene yield 77% from ethane, and best olefins yield 50% from propane), Li-Y2O3 [391] (best ethylene yield 51% from n-butane), Co/N-Al2O3 [287], RE oxide-based catalysts [48,189,190] (best ethylene yield 46% from ethane, and best olefins yield 45% from propane), and perovskite-type halo-oxides (La/Sr/Fe/X/O) [192] (best ethylene yield 57.6%).
Oxycracking of hydrocarbons: Chemistry, technology and economic potential
2005, Applied Catalysis A: GeneralCatalytic oxidative cracking for light olefin production
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