US 2002O161249A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2002/0161249 A1 Mull et al. (43) Pub. Date: Oct. 31, 2002 (54) PREPARATION OF EPOXIDES FROM (21) Appl. No.: 09/792,390 ALKANES USING LANTHANDE-PROMOTED SILVER (22) Filed: Feb. 22, 2001 CATALYSTS Publication Classification (76) Inventors: Guido Mul, Nootdorp (NL); Marianna F. Asaro, Belmont, CA (US); Albert S. (51) Int. Cl." ............................................. C07D 301/02 Hirschon, Menlo Park, CA (US); (52) U.S. Cl. .............................................................. 549/534 Retri B. Wilson JR., Palo Alto, CA (57) ABSTRACT A process is provided for use in the conversion of alkanes Correspondence Address: into alkylene oxides, having particular utility in the conver REED & ASSOCATES Sion of propane to form propylene oxide, using a lanthanide 800 MENLO AVENUE promoted, Supported, Silver catalyst prepared via precipita SUTE 210 tion. A preferred embodiment uses Silver nitrate and MENLO PARK, CA 94025 (US) lanthanum nitrate to form the catalyst on a BaCO Support. Patent Application Publication Oct. 31, 2002 US 2002/0161249 A1 10 O 2000 4000 6000 Time (s) FIG. 1 US 2002/0161249 A1 Oct. 31, 2002 PREPARATION OF EPOXDES FROM ALKANES 0006 Catalysts composed of lanthanum carbonate and USINGLANTHANDE-PROMOTED SILVER chromium oxide have been shown to be active and Selective CATALYSTS at lower temperatures but have only been used in the oxidative dehydrogenation of isobutane, See Hoang et al. TECHNICAL FIELD (1997).J. Catal. 171:313. Carbonate-supported catalysts are currently used in ethylene epoxidation and often contain 0001. This invention relates generally to novel catalysts reduced Silver and an O-alumina carrier. Catalysts of this for use in the direct epoxidation of alkanes to form alkylene nature have been described in U.S. Pat. No. 4,248,740 to oxides, having particular utility in the conversion of propane Mitsuhata et al. and U.S. Pat. No. 4,342,667 to Armstrong et to propylene oxide. The catalyst is prepared via precipitation al. and is a lanthanide-promoted, Supported Silver catalyst. The invention also relates to methods for catalyzing oxidative 0007. It has now been unexpectedly discovered that a chlorination/halodehydrogenation and epoxidation reactions highly Selective catalyst capable of “one-pot' conversion of using the novel catalyst, and to methods for manufacturing an alkane to an alkylene oxide can be obtained by using an the novel catalysts. The invention finds utility in the fields of alkaline earth metal carbonate as a Support in combination catalysis. with a rare earth metal promoter. Also Surprising is the finding that Such catalysts are capable of the Selective BACKGROUND oxidative dehydrogenation of alkanes at temperatures under 400° C. 0002 Conversion of alkanes to oxygenates is typically considered to proceed via Oxidative dehydrogenation of an SUMMARY OF THE INVENTION alkane to an alkene followed by epoxidation of the alkene to provide an oxide in a separate process. A direct method of 0008 Accordingly, it is a primary object of the invention Synthesizing alkylene oxides from an alkane Such as propane to provide a process for the conversion of an alkane to an has not been practical heretofore as activation of the propane alkylene oxide at temperatures less than 400 C. requires high temperatures, which decompose partial oxida 0009 Additional objects, advantages and novel features tion products, particularly propylene oxide, or promote total of the invention will be set forth in part in the description oxidation. which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may 0003) Numerous studies have been conducted investigat ing the oxidative dehydrogenation of alkanes to produce be learned by practice of the invention. alkenes. See, for example, Chaar et al. (1988) J. Catal. 0010. In a first embodiment, a novel process for the 109:463, Siew Hew Sam et al. (1990).J. Catal. 123:417, and conversion of alkane to alkylene oxide is provided wherein Stern et al. (1997) Appl. Catal. A. General, 153:21. Various an alkane and oxygen-containing gas feedstream contacts an magnesium Vanadates are reported to yield propylene with alkaline earth metal carbonate-Supported Silver catalyst particularly high Selectivity and, when a Second oxidic phase comprised of a catalytically effective amount of Silver, and (SbO) is added, selectivities of up to 95% have been a promoting amount of a lanthanide metal promoter, an achieved. Carrazan et al. (1997) ACS Symp. Ser. 638:223. alkali metal halide, an alkali metal nitrate, and an optional The mechanisms by which the oxidative dehydrogenation transition metal promoter. occurs and the interactions responsible for high Selectivity 0011. In another embodiment of the invention, a novel are yet to be identified. process for the conversion of propane to propylene oxide is 0004) Other than vanadium-based catalysts, several provided wherein a propane and oxygen-containing gas molybdenum and niobium catalysts have also been investi feedstream contacts an alkaline earth metal carbonate-Sup gated for use in oxidative dehydrogenation. See, for ported Silver catalyst that has a catalytically effective example, Breitescheidel et al. (1991) Chem. Mater: 3:559, amount of Silver, and a promoting amount of a lanthanide Geenen et al. (1982).J. Catal. 77:499 and Toreis et al. (1987) metal promoter, an alkali metal halide, an alkali metal J. Catal. 108:161. Bettahar et al. (1996) Appl. Catal. A. nitrate, and an optional transition metal promoter. General 145:1 and Kim et al. (1991) Appl. Catal. 70:175 0012. In a further embodiment of the invention, a novel discloses that molybdates of, for example, nickel or cobalt, catalyst composition is provided comprising an alkaline yield acrolein in Substantial amounts, thereby decreasing the earth metal carbonate Support, a catalytically effective Selectivity toward propylene. Niobium oxide, particularly in amount of Silver, an effective promoting amount of a lan combination with Vanadium or molybdenum, has been thanide metal promoter, an effective promoting amount of an shown to have high Selectivity for propylene in the oxidative alkali metal halide, an effective promoting amount an alkali dehydrogenation of propane in Savary et al. (1997).J. Catal. metal nitrate, and a promoting amount of a transition metal 169: 287. promoter. 0005 Catalyst compositions without molybdenum or 0013 In yet another embodiment of the invention, a Vanadium have also been known to perform oxidative dehy novel process for the conversion of alkane to alkene is drogenation. Ji et al. (1996) Catal. Lett. 39:247 and Wang et provided comprising contacting, at a temperature in the al. (1995) J. Catal. 151:155 discuss the selectivity of com range of approximately 200 C. to 400 C., a feedstream, binations of lanthanum oxide, alkaline earth metal, and comprised of alkane and an oxygen-containing gas, and a alkali metal. Unfortunately, temperatures in excess of 400 Supported Silver catalyst, comprised of an inert refractory C. are required for any of the above-mentioned catalysts to Solid Support comprised of alkaline earth metal carbonate, a have significant activity and Such temperatures result in catalytically effective amount of Silver, an effective promot decomposition of the propylene oxide. ing amount of a halide anion, an effective promoting amount US 2002/0161249 A1 Oct. 31, 2002 of a rare earth metal promoter, an effective promoting neous, catalyst. In the present catalyst, the Support is com amount of a Sodium promoter, and an optional effective prised of an alkali earth metal carbonate. promoting amount of a transition metal promoter. 0024. A “promoter” means a component that provides an 0.014. In still another embodiment of the invention, a improvement in one or more of the catalytic properties of the novel process for the conversion of propane to propylene is catalyst, e.g., Selectivity, activity, conversion, Stability, and provided comprising contacting, at a temperature in the yield, as compared to a catalyst not containing the promoter. range of approximately 200 C. to 400 C., a feedstream, “Effective promoting amount’ means an amount of a pro comprised of propane and an OXygen-containing gas, and a moter Sufficient to yield the above-mentioned improvement. Supported Silver catalyst comprised of an inert refractory Solid Support comprised of alkaline earth metal carbonate, a 0025) “Halo" or “halogen” refers to fluoro, chloro, catalytically effective amount of Silver, an effective promot bromo, or iodo, and usually relates to halide Substitution for ing amount of a halide anion, an effective promoting amount a hydrogen atom in an organic compound. Of the halides, of a rare earth metal promoter, an effective promoting chloro and fluoro are generally preferred. amount of a Sodium promoter, and an optional effective promoting amount of a transition metal promoter. 0026 “Optional” or “optionally” means that the Subse quently described event or circumstance may or may not BRIEF DESCRIPTION OF THE DRAWING occur, and that the description includes instances where Said event or circumstance occurs and instances where it does 0.015 FIG. 1 presents a precipitation curve obtained not. For example, the phrase “catalyst containing an optional during catalyst Synthesis, as described in Example 17. transition metal anion' means that a transition metal anion may or may not be present and that the description includes DETAILED DESCRIPTION OF THE catalysts that comprise a transition metal anion and catalysts INVENTION that do not. 0016 Definitions and Nomenclature: 0027. The phrase “redox half-reaction” as used herein 0.017. Before the present compounds, compositions, and refers to half-reactions Such as those found in equations methods are disclosed and described, it is to be understood presented in tables of Standard reduction or oxidation poten that, unless otherwise indicated, this invention is not limited tials, also known as Standard or Single electrode potentials, to specific Support Structures, reagents, methods of prepa of the type found in, for instance, the Handbook of Chem ration, or the like, as Such may vary.