Carbon dioxide hydrogenation catalyst
A carbon dioxide (CO 2 ) hydrogenation catalyst and a method of its preparation. The CO 2 hydrogenation catalyst includes an alkali-metal enriched bauxite residue including calcium carbonate (CaCO 3 ), iron(III) oxide (Fe 2 O 3 ), iron(III) oxyhydroxide (FeO(OH)), aluminum hydroxide (Al(OH) 3 ), sodalite, muscovite, and Na 5 Al 2 CSi 3 O 15 . The CO 2 hydrogenation catalyst further includes 1 weight percent (wt. %) to 10 wt. % potassium based on a total weight of the CO 2 hydrogenation catalyst by inductively coupled plasma optical emission spectroscopy (ICP-OES). The CO 2 hydrogenation catalyst is used in a method of hydrogenating carbon dioxide to produce olefins.
1 . A method of hydrogenating carbon dioxide, the method comprising:
providing a CO 2 hydrogenation catalyst comprising an alkali-metal enriched bauxite residue comprising CaCO 3 , Fe 2 O 3 , FeO(OH), Al(OH) 3 , sodalite, muscovite, Na 5 Al 2 CSi 3 O 15 , and potassium, wherein the potassium is present in the CO 2 hydrogenation catalyst at from 3 wt. % to 5 wt. % potassium based on a total weight of the CO 2 hydrogenation catalyst by ICP-OES;
combining particles of the CO 2 hydrogenation catalyst and a gaseous mixture of CO 2 and H 2 in a reactor; and
reacting at least a portion of the CO 2 and H 2 in the gaseous mixture in the presence of the CO 2 hydrogenation catalyst at a temperature of 200 to 550° C. to form a hydrocarbon mixture comprising a C 2 -C 4 olefin;
wherein the CO 2 hydrogenation catalyst has a surface area of 11 to 16 m 2 /g;
wherein the CO 2 hydrogenation catalyst has a pore volume of 0.015 to 0.025 cm 3 /g;
wherein the CO 2 hydrogenation catalyst has a hydrogen temperature-programmed reduction (H 2 -TPR) of from 400 to 450 micromoles per gram (mol) at a temperature of 200 to 850° C.;
wherein the method has a CO 2 conversion of from 25% to 30% based on a total number of moles of CO, introduced;
and
wherein the method has a C 2 -C 4 olefin selectivity of from 20% to 30%.
2 . The method of claim 1 , wherein the CO 2 hydrogenation catalyst further comprises Al 2 O 3 and TiO 2 .
3 . The method of claim 2 , wherein the TiO 2 is rutile and the Fe 2 O 3 is α-Fe 2 O 3 .
4 . The method of claim 1 , wherein the CO 2 hydrogenation catalyst further comprises AlO(OH).
5 . The method of claim 1 , wherein the CO 2 hydrogenation catalyst has a mean particle size of 0.1 to 10 μm.
6 . The method of claim 1 , further comprising forming the CO 2 hydrogenation catalyst by:
calcining red mud at 300 to 700° C. for 1 to 12 hours to produce a calcined red mud;
treating the calcined red mud with a concentrated acid to produce an acid-treated red mud;
grinding the acid-treated red mud with a potassium source to form a precursor mixture; and
calcining the precursor mixture at 300 to 700° C. for 1 to 12 hours to produce the CO 2 hydrogenation catalyst.
7 . The method of claim 6 , wherein the potassium source comprises potassium nitrate.
8 . The method of claim 6 , wherein the potassium source does not comprise potassium hydroxide.
9 . The method of claim 6 , wherein the concentrated acid is HCl having a concentration of 30% to 38% by weight in water.
10 . The method of claim 1 , wherein the gaseous mixture has a volume ratio of the CO 2 to the H 2 of 1:10 to 10:1.
11 . The method of claim 10 , wherein the gaseous mixture has a volume ratio of the CO 2 to the H 2 of 1:1 to 5:1.
12 . The method of claim 1 , wherein the reacting is performed at a pressure of from 5 to 100 bar.
13 . The method of claim 8 , further comprising activating the CO 2 hydrogenation catalyst by drying the CO 2 hydrogenation catalyst by heating to 400 to 600° C. under flowing nitrogen, and reducing the CO 2 hydrogenation catalyst by heating to 400 to 600° C. in the presence of a reducing gas mixture comprising hydrogen and substantially free of CO 2 ; wherein the hydration catalyst is activated prior to combining particles of the CO 2 hydrogenation catalyst and the gaseous mixture of CO 2 and H 2 in the reactor.