EP-4735407-A1 - METHODS FOR CONVERTING ALKANES TO ALKENES AND STEAM TOLERANT PROMOTED DEHYDROGENATION CATALYSTS

EP4735407A1EP 4735407 A1EP4735407 A1EP 4735407A1EP-4735407-A1

Abstract

A method for converting alkanes to alkenes may include contacting a feed stream comprising alkanes with a promoted dehydrogenation catalyst in a reaction zone in the presence of steam, the promoted dehydrogenation catalyst comprising: zirconia and a metal, wherein the metal is selected from the group consisting of chromium, gallium, iron, and combinations thereof, and silicon. The method further includes converting at least a portion of the alkanes to alkenes, thereby yielding a product stream comprising alkanes, alkenes, and hydrogen, wherein the promoted dehydrogenation catalyst does not require a gaseous oxidant in the feed steam or as a co-feed to catalyze conversion of alkanes to alkenes.

Inventors

KIRILIN, Alexey
TORRENTE, Miguel Rivera
BLANN, KEVIN
Dinh, Kimberly
YANCEY, David F.
POLLEFEYT, Glenn
MALEK, ANDRZEJ

Assignees

Dow Global Technologies LLC

Dates

Publication Date: 20260506
Application Date: 20240626

Claims (1)

85056-WO-PCT/DOW 85056 WO CLAIMS 1. A method for converting alkanes to alkenes, the method comprising: contacting a feed stream comprising alkanes with a promoted dehydrogenation catalyst in a reaction zone in the presence of steam, the promoted dehydrogenation catalyst comprising: zirconia and a metal, wherein the metal is selected from the group consisting of chromium, gallium, iron, and combinations thereof; and silicon; and converting at least a portion of the alkanes to alkenes, thereby yielding a product stream comprising alkanes, alkenes, and hydrogen; wherein the promoted dehydrogenation catalyst does not require a gaseous oxidant in the feed steam or as a co-feed to catalyze conversion of alkanes to alkenes. 2. The method of claim 1, further comprising combusting at least a portion of the hydrogen to yield steam. 3. The method of any of the preceding claims, wherein the dehydrogenation catalyst comprises an alkene selectivity greater than or equal to 40 Cmol%. 4. The method of any of the preceding claims, wherein the promoted dehydrogenation catalyst retains at least some dehydrogenation activity above background dehydrogenation activity under greater than or equal to 5 v.% steam conditions based on a total volume of gaseous components in the reaction zone. 5. The method of any of the preceding claims, further comprising contacting the feed stream comprising alkanes with a selective hydrogen combustion material, wherein the promoted dehydrogenation catalyst and the selective hydrogen combustion material are both present in the reaction zone. 6. The method of any of the preceding claims, wherein the promoted dehydrogenation catalyst comprising zirconia and a metal, wherein the metal is selected from the group consisting of chromium, gallium, iron, and combinations thereof, and silicon, comprises zirconia impregnated with a metal, wherein the metal is selected from the group consisting of chromium, gallium, iron, and combinations thereof, and silicon. 85056-WO-PCT/DOW 85056 WO 7. The method of any of the preceding claims, wherein silicon acts as a promoter for the promoted dehydrogenation catalyst. 8. The method of any of the preceding claims, wherein the promoted dehydrogenation catalyst comprises: 0.5 wt.% to 20 wt.% of the metal selected from the group consisting of chromium, gallium, iron, and combinations thereof; 40 wt.% to 80 wt.% zirconium; and 0.1 wt.% to 15 wt.% silicon, wherein the weight percent is based on a total weight of the promoted dehydrogenation catalyst. 9. The method of any of the preceding claims, wherein the silicon is at least partially derived from colloidal silica, silicon alkoxide, or combinations thereof. 10. The method of any of the preceding claims, wherein the promoted dehydrogenation catalyst is a promoted dehydrogenation catalyst comprising the formula M-Zr-Si-X-Q, wherein M is a metal selected from the group consisting of chromium, gallium, iron, and combinations thereof, X is selected from the group consisting of alkali metals, alkaline earth metals, and combinations thereof, and Q is selected from the group consisting of tin, platinum, boron, lanthanum, cerium, neodymium, samarium, gadolinium, dysprosium, praseodymium, europium, and combinations thereof and combinations thereof. 11. The method of any of the preceding claims, wherein the promoted dehydrogenation catalyst and the feed stream have a mass to mass ratio that is from 5:1 to 200:1. 12. The method of any of the preceding claims, wherein the converting at least a portion of the alkanes to alkenes occurs at a temperature that is less than or equal to 750 °C, a pressure from 1 bara to 20 bara, and a WHSV of from 1 h -1 to 12 h -1 . 13. The method of any of the preceding claims, wherein the method further comprises: removing spent promoted dehydrogenation catalyst from the reaction zone; introducing the spent promoted dehydrogenation catalyst into a regeneration zone; 85056-WO-PCT/DOW 85056 WO regenerating the spent promoted dehydrogenation catalyst, thereby forming regenerated promoted dehydrogenation catalyst; and returning the regenerated promoted dehydrogenation catalyst to the reaction zone where it is contacted with the feed stream. 14. A method for forming a promoted dehydrogenation catalyst, the method comprising: obtaining a zirconia support; adding a silicon-containing precursor to the zirconia support; adding a metal-containing precursor to the zirconia support, wherein the metal- containing precursor is selected from the group consisting of chromium, gallium, iron, and combinations thereof to form a metal-containing zirconia; and calcining and drying the metal-containing zirconia to form a promoted dehydrogenation catalyst; wherein adding the silicon-containing precursor to the zirconia support and adding the metal-containing precursor to the zirconia support occur in any order. 15. The method of claim 14, wherein adding the silicon-containing precursor to the zirconia support is a process selected from the group consisting of: adding the silicon-containing precursor to the zirconia support, wherein the zirconia support is a fluidizable zirconia support; adding the silicon-containing precursor to the zirconia support by spray drying; adding the silicon-containing precursor to the zirconia support; and combinations thereof; and contacting the zirconia support with the metal-containing precursor is a process selected from the group consisting of: adding the metal-containing precursor to the zirconia support, wherein the zirconia support is a fluidizable zirconia support; adding the metal-containing precursor to the zirconia support by spray drying; adding the metal-containing precursor to the zirconia support by granulation; and combinations thereof.

Description

85056-WO-PCT/DOW 85056 WO 1 METHODS FOR CONVERTING ALKANES TO ALKENES AND STEAM TOLERANT PROMOTED DEHYDROGENATION CATALYSTS CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application Serial No. 63/511,263 filed June 30, 2023, the contents of which are incorporated in their entirety herein. TECHNICAL FIELD [0002] The present disclosure relates to methods for efficiently converting various alkanes to alkenes. In particular, the present disclosure relates to the preparation of promoted dehydrogenation catalysts, and more particularly, silicon promoted dehydrogenation catalysts that tolerate steam, and methods of using the promoted dehydrogenation catalysts to achieve a high conversion of alkanes to alkenes in the presence of steam. BACKGROUND [0003] Alkenes are used for a wide range of industrial applications, including producing plastics, fuels, and various downstream chemicals. Such alkenes include C2 to C4 materials, including ethene, propene, and butenes (also commonly referred to as ethylene, propylene, and butylenes, respectively). A variety of processes for producing these alkenes have been developed, including petroleum cracking and various synthetic processes. [0004] One such process for producing alkenes is alkane dehydrogenation. Conventional alkane dehydrogenation is endothermic and equilibrium limited. Therefore, to reach economically feasible levels of alkane-to-alkene conversion, conventional alkane dehydrogenation necessitates the use of low pressures to shift the equilibrium toward producing products and high temperatures, often in excess of 800 oC, to provide thermal energy. Additionally, conventional alkane dehydrogenation processes suffer from additional undesirable radical chemistry that may produce coke as a byproduct. The formation of coke may cause blockages, which may require periodic process shutdowns for decoking operations. 85056-WO-PCT/DOW 85056 WO 2 [0005] Maintaining the low pressures and high temperatures necessary for economically feasible alkane-to-alkene conversion can be expensive. Accordingly, a need exists for methods and catalytic systems with high alkene selectivity that operate at higher pressures and lower temperatures while reaching economically feasible levels of alkane-to-alkene conversion. SUMMARY [0006] Embodiments of the present disclosure address these and other needs by the methods of preparation of promoted dehydrogenation catalysts, and more particularly, silicon-promoted dehydrogenation catalysts that are capable of performing dehydrogenation chemistry in the presence of steam, and methods of using such promoted dehydrogenation catalysts. A promoted dehydrogenation catalyst, as described herein, comprises zirconia (ZrO2) and a metal selected from the group consisting of chromium (Cr), gallium (Ga), iron (Fe), and combinations thereof, and silicon (Si). This promoted dehydrogenation catalyst may then be used for converting alkanes to alkenes. The promoted dehydrogenation catalyst may be able to catalyze the conversion of alkanes to alkenes in the presence of steam. [0007] According to one or more embodiments of the present disclosure, a method for converting alkanes to alkenes may comprise contacting a feed stream comprising alkanes with a promoted dehydrogenation catalyst in a reaction zone in the presence of steam, the promoted dehydrogenation catalyst comprising zirconia and a metal selected from the group consisting of chromium, gallium, iron, and combinations thereof, and silicon, converting at least a portion of the alkanes to alkenes, thereby yielding a product stream comprising alkanes, alkenes, and hydrogen. [0008] According to one or more embodiments of the present disclosure, a method for forming a promoted dehydrogenation catalyst may comprise obtaining a zirconia support, adding a silicon- containing precursor to the zirconia support, adding a metal-containing precursor to the zirconia support, wherein the metal-containing precursor is selected from the group consisting of chromium, gallium, iron, and combinations thereof, to form a metal-containing zirconia, and calcining and drying the metal-containing zirconia to form a promoted dehydrogenation catalyst, wherein adding a silicon-containing precursor to the zirconia support and adding a metal- containing precursor to the zirconia support occur in any order. 85056-WO-PCT/DOW 85056 WO 3 [0009] Additional features and advantages will be set forth in the detailed description that follows and, in part, will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows in addition to the claims. [0010] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and chara