Methods and compositions for production of CO
In one aspect, the disclosure relates to relates to CO 2 -free methods of co-producing hydrogen and solid forms of carbon via methane decomposition. The methods are efficient, self-sustaining, and environmentally sound. In a further aspect, the disclosure relates to recyclable and recoverable catalysts supported by solid forms of carbon and methods for recycling the catalysts. In some aspects, the disclosure relates to catalysts that do not require support by solid forms of carbon. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.
1 . A method for producing hydrogen from methane, the method comprising:
using a catalyst comprising (i) nickel and (ii) a second metal selected from copper or palladium to decompose methane into a product carbon and hydrogen at a reaction temperature ranging from 500° C. to 600° C. for a reaction time period, wherein the nickel and the second metal are present in amounts that provide a weight ratio of nickel to the second metal of 5:1 to 10:1 (nickel:second metal);
combining the product carbon and the catalyst with nitric acid having a concentration of at least 2M to form a mixture;
stirring the mixture at a temperature of at least 120° C., wherein the nitric acid causes metal ions or atoms from the catalyst to separate from the product carbon such that at least 86% of the total amount of metal ions or atoms are removed from the product carbon;
removing the metal ions or atoms from the mixture;
removing the product carbon from the mixture; and
using from about 50 wt % to about 95 wt % of the product carbon to restart the method.
2 . The method of claim 1 , further comprising:
(i) admixing one or more catalyst precursor compounds in a solvent to produce a metal-precursor solution;
(ii) removing the solvent from the catalyst precursor compounds to form the catalyst;
(iii) collecting the hydrogen; or
(iv) any combination of two or more of (i), (ii), or (iii).
3 . The method of claim 2 , wherein the metal-precursor solution further comprises a seed carbon support; and wherein nitric acid is used to cause the catalyst precursor compounds to separate from the seed carbon support.
4 . The method of claim 3 , wherein the method further comprises removing the seed carbon support from the metal-precursor solution.
5 . The method of claim 3 , wherein the seed carbon support is used in the method after being treated with the nitric acid.
6 . The method of claim 3 , wherein the seed carbon support is used in the method without pretreatment.
7 . The method of claim 3 , wherein the metal-precursor solution is heated at a synthesis temperature for a synthesis time period to produce the catalyst, wherein the catalyst is supported on the seed carbon support.
8 . The method of claim 3 , wherein the seed carbon support comprises nanoparticles, fullerenes, carbon filaments, single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, or a combination thereof.
9 . The method of claim 1 , wherein the product carbon comprises nanoparticles, fullerenes, carbon filaments, single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, or a combination thereof.
10 . The method of claim 1 , wherein the catalyst is obtained from a catalyst precursor compound, which comprises a nickel salt, a palladium salt a copper salt, or a combination thereof.
11 . The method of claim 10 , wherein the copper salt comprises CuSO 4 , CuCl 2 , Cu(NO 3 ) 2 , Cu(NO 3 ) 2 ·3H 2 O, CuO, Cu(CH 3 COO) 2 , Cu 3 (PO 4 ) 2 , Cu(ClO 4 ) 2 , CuO 2 , Cu(hfac) 2 , CuO 3 Si, Cu(CO 2 CH 3 ), Cu(NH 3 ) 4 , Cu(SCN) 2 , Cu(NH 3 ) 4 SO 4 ·H 2 O, Cu(OH) 2 , CuBr 2 , or a combination thereof.
12 . The method of claim 10 , wherein the nickel salt comprises Ni(NO 3 ) 2 ·6H 2 O, NiCl 2 , NiCl 2 ·6H 2 O, NiBr 2 , NiF 2 , NiBr 2 ·xH 2 O, NiBr 2 ·3H 2 O, or a combination thereof.
13 . The method of claim 10 , wherein the palladium salt comprises Pd(NO 3 ) 2 ·2H 2 O, PdCl 2 , 4PdSO 4 , PdI 2 , (CF 3 CO 2 ) 2 Pd, C 10 H 18 O 4 Pd, Pd(NO 3 ) 2 , Pd(NO 3 ) 2 ·4NH 3 , Pd(C 2 H 3 O 2 ) 2 ·4NH 3 ·2H 2 O, Pd(CHO 3 ) 2 ·4NH 3 , Pd(NH 3 ) 4 Cl 2 ·H 2 O, (C 2 H 5 CO 2 ) 2 Pd, or a combination thereof.
14 . The method of claim 10 , wherein the catalyst precursor compound comprises Ni(NO 3 ) 2 ·6H 2 O and Pd(NO 3 ) 2 ·2H 2 O.
15 . The method of claim 10 , wherein the catalyst precursor compound comprises Ni(NO 3 ) 2 ·6H 2 O and Cu(NO 3 ) 2 ·6H 2 O.
16 . The method of claim 1 , wherein the catalyst is bimetallic.
17 . The method of claim 16 , wherein the catalyst comprises nickel and palladium, wherein the nickel and palladium are present in amounts that provide a weight ratio of nickel to palladium of 10:1; or wherein the catalyst comprises nickel and copper, wherein the copper and nickel are present in amounts that provide a weight ratio of nickel to copper of 10:1.
18 . The method of claim 1 , wherein the method has a first pass conversion; and wherein the first pass conversion results in at least 5% of the methane being converted.