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Title: Process economics and safety considerations for the oxidative dehydrogenation of ethane using the M1 catalyst

Abstract

Olefins or unsaturated hydrocarbons play a vital role as feedstock for many industrially significant processes. Ethylene is the simplest olefin and a key raw material for consumer products. Oxidative Dehydrogenation (ODH) is one of the most promising new routes for ethylene production that can offer a significant advantage in energy efficiency over the conventional steam pyrolysis process. This study is focused on the ODH chemistry using the mixed metal oxide MoVTeNbOx catalysts, generally referred to as M1 for the key phase known to be active for dehydrogenation. Using performance results from the patent literature a series of process simulations were conducted to evaluate the effect of feed composition on operating costs, profitability and process safety. The key results of this study indicate that the ODH reaction can be made safer and more profitable without use of an inert diluent and furthermore by replacing O2 with CO2 as an oxidant. Modifications of the M1 catalyst composition in order to adopt these changes are discussed.

Authors:
; ;
Publication Date:
Research Org.:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1361427
Report Number(s):
INL/JOU-16-40770
Journal ID: ISSN 0920-5861; PII: S0920586117303528
DOE Contract Number:
DE-AC07-05ID14517
Resource Type:
Journal Article
Resource Relation:
Journal Name: Catalysis Today
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 02 PETROLEUM; 04 OIL SHALES AND TAR SANDS; comparative techno-economic analysis; comprehensive inherent safety index (CISI); Oxidative Dehydrogenation (ODH); process safety analysis

Citation Formats

Baroi, Chinmoy, Gaffney, Anne M., and Fushimi, Rebecca. Process economics and safety considerations for the oxidative dehydrogenation of ethane using the M1 catalyst. United States: N. p., 2017. Web. doi:10.1016/j.cattod.2017.05.041.
Baroi, Chinmoy, Gaffney, Anne M., & Fushimi, Rebecca. Process economics and safety considerations for the oxidative dehydrogenation of ethane using the M1 catalyst. United States. doi:10.1016/j.cattod.2017.05.041.
Baroi, Chinmoy, Gaffney, Anne M., and Fushimi, Rebecca. 2017. "Process economics and safety considerations for the oxidative dehydrogenation of ethane using the M1 catalyst". United States. doi:10.1016/j.cattod.2017.05.041. https://www.osti.gov/servlets/purl/1361427.
@article{osti_1361427,
title = {Process economics and safety considerations for the oxidative dehydrogenation of ethane using the M1 catalyst},
author = {Baroi, Chinmoy and Gaffney, Anne M. and Fushimi, Rebecca},
abstractNote = {Olefins or unsaturated hydrocarbons play a vital role as feedstock for many industrially significant processes. Ethylene is the simplest olefin and a key raw material for consumer products. Oxidative Dehydrogenation (ODH) is one of the most promising new routes for ethylene production that can offer a significant advantage in energy efficiency over the conventional steam pyrolysis process. This study is focused on the ODH chemistry using the mixed metal oxide MoVTeNbOx catalysts, generally referred to as M1 for the key phase known to be active for dehydrogenation. Using performance results from the patent literature a series of process simulations were conducted to evaluate the effect of feed composition on operating costs, profitability and process safety. The key results of this study indicate that the ODH reaction can be made safer and more profitable without use of an inert diluent and furthermore by replacing O2 with CO2 as an oxidant. Modifications of the M1 catalyst composition in order to adopt these changes are discussed.},
doi = {10.1016/j.cattod.2017.05.041},
journal = {Catalysis Today},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 5
}
  • The addition of chloride ions to a Li{sup +}-MgO catalyst at a ratio of Cl/Li {>=} 0.9 significantly improves the yields of ethylene that can be achieved during the oxidative dehydrogenation (OXD) of ethane. At 620{degrees}C, C{sub 2}H{sub 4} yields of 58% (75% conversion, 77% selectivity) have been maintained for up to 50 h on stream. These ethylene yields are consistent with the large C{sub 2}H{sub 4}/{sub 2}H{sub 6} ratios that are attained over these catalysts during the oxidative coupling of CH{sub 4}. The activity of the catalysts with Cl/Li {>=} 0.9 is partly a result of the fact CO{submore » 2} formed during the reaction does not poison the catalyst. In addition, the surface areas of the chlorided catalysts are greater than those which contain a comparable amount of Li, but no chloride ions. Based upon the activity results, CO{sub 2} temperature-programmed desorption data, and X-ray photoelectron spectra, a model has been proposed in which lithium is mainly present as LiCl on the MgO support, provided a nearly stoichiometric amount of chloride is available. The active centers are believed to be associated with a thin (atomic) layer of Li{sub 2}O that partially covers the LiCl crystallites. This Li{sub 2}O is capable of activating {sub 2}H{sub 6}, but its basic strength has been modified so that it does not form carbonate ions at 620{degrees}C. When the amount of chloride is limited, or is not present at all, multilayers of more strongly basic Li{sub 2}O form on the surface of LiCl and/or on the MgO. In the presence of CO{sub 2}, this Li{sub 2}O is extensively converted to Li{sub 2}CO{sub 3}, which is inactive for the OXD reaction. 20 refs., 9 figs., 6 tabs.« less
  • The catalytic properties of Al2O3-supported vanadia with a wide range of VOx surface density (1.4-34.2 V/nm2) and structure were examined for the oxidative dehydrogenation of ethane and propane. UV-visible and Raman spectra showed that vanadia is dispersed predominantly as isolated monovanadate species below {approx}2.3 V/nm2. As surface densities increase, two-dimensional polyvanadates appear (2.3-7.0 V/nm2) along with increasing amounts of V2O5 crystallites at surface densities above 7.0 V/nm2. The rate constant for oxidative dehydrogenation (k1) and its ratio with alkane and alkene combustion (k2/k1 and k3/k1, respectively) were compared for both alkane reactants as a function of vanadia surface density. Propenemore » formation rates (per V-atom) are {approx}8 times higher than ethene formation rates at a given reaction temperature, but the apparent ODH activation energies (E1) are similar for the two reactants and relatively insensitive to vanadia surface density. Ethene and propene formation rates (per V-atom) are strongly influenced by vanadia surface density and reach a maximum value at intermediate surface densities ({approx}8 V/nm2). The ratio of k2/k1 depends weakly on reaction temperature, indicating that activation energies for alkane combustion and ODH reactions are similar. The ratio of k2/k1 is independent of surface density for ethane, but increase slightly with vanadia surface density for propane, suggesting that isolated structures prevalent at low surface densities are slightly more selective for alkane dehydrogenation reactions. The ratio of k3/k1 decreases markedly with increasing reaction temperature for both ethane and propane ODH. Thus, the apparent activation energy for alkene combustion (E3) is much lower than that for alkane dehydrogenation (E1) and the difference between these two activation energies decreases with increasing surface density. The lower alkene selectivities observed at high vanadia surface densities are attributed to an increase in alkene adsorption enthalpies with increasing vanadia surface density. The highest yield of alkene is obtained for catalysts containing predominantly isolated monovanadate species and operated at high temperatures that avoid homogeneous reactions (< {approx} 800 K).« less
  • Lithium-promoted magnesium oxide is an effective catalyst for the conversion of ethane to ethylene. A selectivity of 75% for ethylene was obtained at 40% ethane conversion over 6.5 g of 3 wt% Li{sup +}/MgO catalyst at 600 C. These results were obtained with initial pressures of 95 Torr C{sub 2}H{sub 6} and 47 Torr O{sub 2} at a space velocity of 260 h{sup {minus}1}. An apparent activation energy of 37.3 kcal mol{sup {minus}1} was observed for this process. The carbon oxides are formed both by the direct oxidation of ethane and the secondary oxidation of ethylene. In the reactor employedmore » in this study homogeneous reactions became dominant at temperatures greater than 675 C. The catalytic system is believed to involve the generation of C{sub 2}H{sub 5} {center dot} radicals on the surface, followed by the emanation of these radicals into the gas phase where they react with O{sub 2} to form C{sub 2}H{sub 4}. The ability of this catalyst to generate alkyl radicals from CH{sub 4} or C{sub 2}H{sub 6} appears to be a general phenomenon. The subsequent reactions of these alkyl radicals (e.g., coupling or reaction with O{sub 2}) determines to a large extent the final product distribution. Ethylene also may be formed via surface ethoxide ions.« less
  • An inert-membrane catalytic reactor has been tested for the oxidative dehydrogenation of ethane. This reactor consists of a fixed bed of Li/MgO catalyst encompassed by a porous ceramic membrane. Oxygen was permeated through the membrane while ethane was fed axially. Two different configurations of the membrane reactor were tested: a homogeneous wall membrane reactor and a mixed system which was equivalent to a membrane reactor followed by a conventional fixed bed reactor. Using this system, high conversions of ethane were obtained, while maintaining a good selectivity. This gave yields to ethylene and higher hydrocarbons of up to 57%. In addition,more » the membrane reactor allowed a safe and stable operation, even when a relatively high proportion of oxygen was used in the overall feed.« less