Method of preparing catalyst for oxidative dehydrogenation

Patent metadata

Field	Value
Publication number	US-10926246-B2
Application number	US-201715744721-A
Country	US
Kind code	B2
Filing date	Mar 15, 2017
Priority date	Mar 18, 2016
Publication date	Feb 23, 2021
Grant date	Feb 23, 2021

Abstract

The present invention relates to a method of preparing a catalyst for oxidative dehydrogenation. More particularly, the present invention provides a method of preparing a catalyst for oxidative dehydrogenation providing superior selectivity and yield for a conjugated diene according to oxidative dehydrogenation by constantly maintaining pH of a coprecipitation solution using a drip-type double precipitation method to adjust an α-iron oxide content in a catalyst in a predetermined range.

First claim

The invention claimed is:

1. A method of preparing a catalyst for oxidative dehydrogenation, the method comprising:
(a) preparing an aqueous precursor solution by dissolving in water a trivalent cation iron (Fe) precursor and a divalent cation zinc (Zn) precursor in a mole ratio of Fe:Zn of 3:1-5:1 and having a combined total concentration of 5 wt % to 8 wt %, wherein the trivalent cation iron (Fe) precursor and the divalent cation zinc (Zn) precursor each independently is a nitrate, an ammonium salt, a sulfate, or a chloride, wherein a pH of the aqueous precursor solution is 0 to 4;
(b) forming a coprecipitation solution by feeding dropwise, the aqueous precursor solution into an aqueous 25% to 40% by weight ammonia solution in a coprecipitation tank while constantly maintaining a pH of the coprecipitation solution by feeding an aqueous 25% to 40% by weight ammonia solution dropwise along with the aqueous precursor solution;
(c) obtaining a coprecipitate by filtering the coprecipitation solution; and
(d) drying, firing, or drying and firing the coprecipitate obtained in step (c) to yield the catalyst.

2. The method according to claim 1 , wherein, in step (b), the aqueous precursor solution and the aqueous ammonia solution are added dropwise from separate outlets.

3. The method according to claim 1 , wherein, in step (b), the aqueous precursor solution is fed dropwise into the coprecipitation tank at a rate of 40 g/min or more.

4. The method according to claim 1 , wherein, in step (b), the pH of the coprecipitation solution is maintained at greater than 8 and less than 11.

5. The method according to claim 1 , wherein step (b) further comprises stirring the coprecipitation solution to which the aqueous precursor solution has been added.

6. The method according to claim 1 , wherein the coprecipitate is dried in a drier at a temperature of 60° C. to 100° C. for 12 to 20 hours to yield a dried coprecipitate, and the dried coprecipitate is fired in a firing furnace at a temperature of 400° C. to 800° C. for 1 to 10 hours to yield the catalyst which contains 46% by weight ZnFe 2 O 4 and 54% by weight Fe 2 O 3 .

7. A method of preparing a catalyst for oxidative dehydrogenation, the method comprising:
(a) preparing an aqueous precursor solution by dissolving in water a trivalent cation iron (Fe) precursor and a divalent cation metal (A) precursor containing a divalent cation metal A selected from the group consisting of copper (Cu), radium (Ra), barium (Ba), strontium (Sr), calcium (Ca), beryllium (Be), zinc (Zn), manganese (Mn), and cobalt (Co) in a mole ratio of Fe:A of 3:1 to 5:1 and having a combined total concentration of 5 wt % to 8 wt %, wherein the trivalent cation iron (Fe) precursor and the divalent cation metal (A) precursor each independently is a nitrate, an ammonium salt, a sulfate, or a chloride;
(b) forming a coprecipitation solution by feeding dropwise the aqueous precursor solution into a 28% by weight basic aqueous ammonia solution in a coprecipitation tank while constantly maintaining a pH of the coprecipitation solution by feeding a 28% by weight basic aqueous ammonia solution dropwise along with the aqueous precursor solution;
(c) obtaining a coprecipitate by filtering the coprecipitation solution; and
(d) drying, firing, or drying and firing the coprecipitate obtained in step (c) to yield the catalyst.

Assignees

• Lg Chemical Ltd

Inventors

• Han Jun Kyu
• Ko Dong Hyun
• Cha Kyong Yong
• Suh Myung Ji
• Hwang Sun Hwan
• Kim Seong Min

Classifications

• B01J37/031 Primary

  Precipitation · CPC title

• B01J35/77

  Compounds characterised by their crystallite size · CPC title

• B01J23/80

  with zinc, cadmium or mercury · CPC title

• B01J21/10

  Magnesium; Oxides or hydroxides thereof · CPC title

• C07C2523/80

  with zinc, cadmium or mercury · CPC title