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US-12617690-B2 - Crystalline boehmite materials as precursors for large crystal gamma alumina and low surface area alpha alumina

US12617690B2US 12617690 B2US12617690 B2US 12617690B2US-12617690-B2

Abstract

A process for preparing crystalline boehmite includes combining a stoichiometric amount of flash calcined gibbsite (AI 2 O 3 ) and gibbsite (Al(OH) 3 ) in a pressurizable reaction vessel; heating the flash calcined gibbsite and gibbsite in the reaction vessel to a temperature of about 200° C. to about 280° C. and for a time sufficient to form crystalline boehmite. A crystalline boehmite exhibiting a crystallite from about 600 Å to about 850 Å when measured in the 120 direction of the crystallographic space group Cmcm.

Inventors

  • KARL C. KHARAS
  • Danna Mooney

Assignees

  • BASF CORPORATION

Dates

Publication Date
20260505
Application Date
20210916

Claims (13)

  1. 1 . A process for preparing crystalline boehmite, the process comprising: combining a stoichiometric amount of flash calcined gibbsite (Al 2 O 3 ) and gibbsite (Al(OH) 3 ) in a pressurizable reaction vessel; heating the flash calcined gibbsite and gibbsite in the reaction vessel to a temperature of about 200° C. to about 280° C. and for a time sufficient to form crystalline boehmite wherein the combining of the stoichiometric amount of flash calcined gibbsite and gibbsite is at a 1:1 molar ratio of flash calcined gibbsite Al 2 O 3 to gibbsite Al(OH) 3 .
  2. 2 . The process of claim 1 , wherein the temperature is from about 200° C. to about 260° C.
  3. 3 . The process of claim 1 , wherein the heating occurs for a time sufficient to form at least about 5 mol % of crystalline boehmite based on the total amount of solids.
  4. 4 . The process of claim 1 , wherein the time sufficient to form crystalline boehmite is at least about 30 minutes.
  5. 5 . The process of claim 1 , wherein the time sufficient to form crystalline boehmite is about 30 minutes to about 1 week.
  6. 6 . The process of claim 1 , wherein the pressurized vessel is configured to prevent or minimize the release of steam from the vessel.
  7. 7 . The process of claim 1 , wherein the crystalline boehmite exhibits a crystallite size of about 600 Å to about 850 Å.
  8. 8 . The process of claim 1 , wherein about 10 mol % to about 100 mol % of crystalline boehmite is formed based on the total amount of solids.
  9. 9 . The process of claim 1 , further comprising doping the crystalline boehmite with a rare earth element, bismuth, an alkaline earth metal, or a mixture of any two or more thereof.
  10. 10 . The process of claim 1 , wherein the flash calcined gibbsite contains up to about 15 wt % water.
  11. 11 . A process for preparing a transitional alumina, the process comprising: preparing crystalline boehmite via a process comprising: combining a stoichiometric amount of flash calcined gibbsite (Al 2 O 3 ) and gibbsite (Al(OH) 3 ) in a pressurizable reaction vessel; heating the flash calcined gibbsite and gibbsite in the reaction vessel to a temperature of about 200° C. to about 280° C. and for a time sufficient to form crystalline boehmite; and calcining the crystalline boehmite to form the transitional alumina wherein the combining of the stoichiometric amount of flash calcined gibbsite and gibbsite is at a 1:1 molar ratio of flash calcined gibbsite Al 2 O 3 to gibbsite Al(OH) 3 .
  12. 12 . The process of claim 11 , wherein the calcining is conducted at a temperature of about 400° F. to about 1200° F.
  13. 13 . The process of claim 11 , wherein the transitional alumina comprises γ-alumina.

Description

CROSS REFERENCE TO RELATED APPLICATION(S) The present application is a national stage entry under 35 U.S.C. § 371 of International Application No. PCT/US2021/050749, filed on Sep. 16, 2021, which claims priority to U.S. Provisional Patent Application No. 63/084,835, filed on Sep. 29, 2020, the entire contents of which are incorporated herein by reference in their entirety. FIELD The present technology relates to a process of preparing crystalline boehmite (AlOOH) and transitional aluminas from flash calcined gibbsite. In particular, the present technology relates to a process for preparing crystalline boehmite from reacting flash calcined gibbsite and gibbsite at stoichiometric ratios. SUMMARY In one aspect, provided is a crystalline boehmite exhibiting a crystallite from about 600 Å to about 850 Å when measured in the 120 direction of the crystallographic space group Cmcm. According to various embodiments, the crystallite size is from about 650 Å to about 850 Å, or from about 660 Å to about 760 Å. In another aspect, a process is provided for preparing crystalline boehmite, the process includes combining a stoichiometric amount of flash calcined gibbsite (Al2O3) and gibbsite (Al(OH)3) in a pressurizable reaction vessel, and heating the flash calcined gibbsite and gibbsite in the reaction vessel to a temperature of about 200° C. to about 280° C. and for a time sufficient to form crystalline boehmite. In any such embodiments, the heating may occur for a time sufficient to form at least about 5 mol % of crystalline boehmite based on the total amount of solids. In any such embodiments, the time sufficient to form crystalline boehmite may be at least about 30 minutes. In any such embodiments, the time sufficient to form crystalline boehmite may be about 30 minutes to about 1 week. In any such embodiments, the pressurized vessel is configured to prevent or minimize the release of steam from the vessel. In any such embodiments, the crystalline boehmite prepared may exhibit a crystallite size of about 600 Å to about 850 Å. In any such embodiments, the process may also include doping the crystalline boehmite with a rare earth element, bismuth, an alkaline earth metal, or a mixture of any two or more thereof. In another aspect, a process is provided for preparing a transitional alumina, the process including preparing crystalline boehmite via a stoichiometric process that includes combining stoichiometric amounts of flash calcined gibbsite (Al2O3) and gibbsite (Al(OH)3) in a pressurized reaction vessel; heating the flash calcined gibbsite and gibbsite in the reaction vessel to a temperature of about 200° C. to about 280° C. and for a time sufficient to form crystalline boehmite; and calcining the crystalline boehmite to form the transitional alumina. In any such embodiments, the calcining may be conducted at a temperature of about 400° F. to about 1200° F., or a temperature of about 450° F. to about 750° F., or a temperature of about 700° F. to about 1100° F. In any such embodiments, the transitional alumina may include γ-alumina. In any such embodiments, the process may also include doping the transitional alumina with a rare earth element, bismuth, an alkaline earth metal, or a mixture of any two or more thereof. In another aspect, a composition is provided that includes any of the herein described crystalline boehmites or transitional aluminas, wherein the composition is selected from fluid catalyst cracking (FCC) catalysts, catalysts for preparing ethylene oxide, and emissions control catalysts. In another aspect, an FCC catalyst includes Y-zeolite and any of the above crystalline boehmites exhibiting a crystallite size of about 600 Å to about 850 Å. Such composition may further include a transitional alumina. In any such embodiments, the FCC catalyst may include from about 5 wt. % to about 60 wt. % of the Y-zeolite based on total weight of the FCC catalyst. In another aspect, a composition is provided that includes any of the above crystalline boehmites, or prepared crystalline boehmites, a transitional alumina as described or prepared herein, the composition is selected from fluid catalyst cracking (FCC) catalysts, catalysts for preparing ethylene oxide, and emissions control catalysts. In another aspect, a FCC catalyst is provided that includes a Y-zeolite and a crystalline boehmite having a crystallite size of about 200 Å to about 850 Å. In any such embodiments, the catalyst may include microspherical support that includes the crystalline boehmite. In any such embodiments, the FCC catalyst may further include a transitional alumina prepared according to any of the processes described herein. In any such embodiments, the FCC catalyst includes from about 5 wt. % to about 60 wt. % of the Y-zeolite based on total weight of the FCC catalyst. In any such embodiments, the FCC catalyst may further include one or more of a rare earth element, bismuth, or an alkaline earth metal. In any such embodiments, the FCC cataly