Non-precious bimetallic catalysts for selective dehydrogenation of an organic chemical hydride system

Abstract

Methylcyclohexane (MCH)-toluene (TOL) chemical hydride cycles as hydrogen carrier systems are successful with the selective dehydrogenation of MCH to TOL, which has been achieved only using precious Pt-based catalysts. Herein, we report improved selectivity using non-precious metal nickel-based bimetallic catalysts, where the second metal occupies the unselective step sites.

Ni–Cu High-Loaded Sol–Gel Catalysts for Dehydrogenation of Liquid Organic Hydrides: Insights into Structural Features and Relationship with Catalytic Activity

“…A detailed analysis of the observed experimental tendencies is described elsewhere [ 36 ]. As seen in Table 2 , the monometallic nickel-based catalyst exhibited the lowest selectivity toward TOL formation among the catalysts tested, which is in good agreement with the previous results on the dehydrogenation of cycloalkanes [ 22 , 27 , 37 ]. It can also be seen that the addition of copper positively affects the selectivity of MCH conversion routes.…”

Ni–Cu High-Loaded Sol–Gel Catalysts for Dehydrogenation of Liquid Organic Hydrides: Insights into Structural Features and Relationship with Catalytic Activity

“…A detailed analysis of the observed experimental tendencies is described elsewhere [ 36 ]. As seen in Table 2 , the monometallic nickel-based catalyst exhibited the lowest selectivity toward TOL formation among the catalysts tested, which is in good agreement with the previous results on the dehydrogenation of cycloalkanes [ 22 , 27 , 37 ]. It can also be seen that the addition of copper positively affects the selectivity of MCH conversion routes.…”

Kinetics on NiZn Bimetallic Catalysts for Hydrogen Evolution via Selective Dehydrogenation of Methylcyclohexane to Toluene

“…The position of peaks of all the catalysts are found to be comparable. Consistent with the small particle size obtained from the STEM images (Figure ), the metallic (or alloy) peaks of both catalysts were not clearly visible and overlapped with the peaks of the γ-Al 2 O 3 support as reported …”

“…Under the same condition, the monometallic Ni catalyst shows similar conversions, and the selectivity was also high for CH to BZ, but a slight loss of selectivity was observed for MCH to TOL (∼97%) due to formation of CH 4 and BZ as a consequence of C–C cleavage of the methyl group. The selectivity loss was from both primary (directly from MCH) and secondary (TOL) reactions, as reported in our previous communication . Based on this result, the partial pressure dependence was measured after the stability test of 12 h.…”

High-Loaded Nickel Based Sol–Gel Catalysts for Methylcyclohexane Dehydrogenation

“…It is evident that with increasing reaction temperature, MCH conversion increases as well in the presence of the monometallic nickel-based catalyst. At that, an extremely low selectivity to toluene formation is observed, in agreement with previously reported results for the dehydrogenation of cycloalkanes over a monometallic nickel catalyst [18,24]. The main by-products are methane and benzene, which is indicative of the competing dealkylation of MCH with increasing temperature.…”

Ni–Cu High-Loaded Sol–Gel Catalysts for Dehydrogenation of Liquid Organic Hydrides: Insights into Structural Features and Relationship with Catalytic Activity

“…A detailed analysis of the observed experimental tendencies is described elsewhere [ 36 ]. As seen in Table 2 , the monometallic nickel-based catalyst exhibited the lowest selectivity toward TOL formation among the catalysts tested, which is in good agreement with the previous results on the dehydrogenation of cycloalkanes [ 22 , 27 , 37 ]. It can also be seen that the addition of copper positively affects the selectivity of MCH conversion routes.…”

Kinetics on NiZn Bimetallic Catalysts for Hydrogen Evolution via Selective Dehydrogenation of Methylcyclohexane to Toluene

“…The position of peaks of all the catalysts are found to be comparable. Consistent with the small particle size obtained from the STEM images (Figure ), the metallic (or alloy) peaks of both catalysts were not clearly visible and overlapped with the peaks of the γ-Al 2 O 3 support as reported …”

“…Under the same condition, the monometallic Ni catalyst shows similar conversions, and the selectivity was also high for CH to BZ, but a slight loss of selectivity was observed for MCH to TOL (∼97%) due to formation of CH 4 and BZ as a consequence of C–C cleavage of the methyl group. The selectivity loss was from both primary (directly from MCH) and secondary (TOL) reactions, as reported in our previous communication . Based on this result, the partial pressure dependence was measured after the stability test of 12 h.…”

High-Loaded Nickel Based Sol–Gel Catalysts for Methylcyclohexane Dehydrogenation

“…It is evident that with increasing reaction temperature, MCH conversion increases as well in the presence of the monometallic nickel-based catalyst. At that, an extremely low selectivity to toluene formation is observed, in agreement with previously reported results for the dehydrogenation of cycloalkanes over a monometallic nickel catalyst [18,24]. The main by-products are methane and benzene, which is indicative of the competing dealkylation of MCH with increasing temperature.…”

Ni–Cu High-Loaded Sol–Gel Catalysts for Dehydrogenation of Liquid Organic Hydrides: Insights into Structural Features and Relationship with Catalytic Activity

“…A detailed analysis of the observed experimental tendencies is described elsewhere [ 36 ]. As seen in Table 2 , the monometallic nickel-based catalyst exhibited the lowest selectivity toward TOL formation among the catalysts tested, which is in good agreement with the previous results on the dehydrogenation of cycloalkanes [ 22 , 27 , 37 ]. It can also be seen that the addition of copper positively affects the selectivity of MCH conversion routes.…”

Kinetics on NiZn Bimetallic Catalysts for Hydrogen Evolution via Selective Dehydrogenation of Methylcyclohexane to Toluene

“…The position of peaks of all the catalysts are found to be comparable. Consistent with the small particle size obtained from the STEM images (Figure ), the metallic (or alloy) peaks of both catalysts were not clearly visible and overlapped with the peaks of the γ-Al 2 O 3 support as reported …”

“…Under the same condition, the monometallic Ni catalyst shows similar conversions, and the selectivity was also high for CH to BZ, but a slight loss of selectivity was observed for MCH to TOL (∼97%) due to formation of CH 4 and BZ as a consequence of C–C cleavage of the methyl group. The selectivity loss was from both primary (directly from MCH) and secondary (TOL) reactions, as reported in our previous communication . Based on this result, the partial pressure dependence was measured after the stability test of 12 h.…”

High-Loaded Nickel Based Sol–Gel Catalysts for Methylcyclohexane Dehydrogenation

“…It is evident that with increasing reaction temperature, MCH conversion increases as well in the presence of the monometallic nickel-based catalyst. At that, an extremely low selectivity to toluene formation is observed, in agreement with previously reported results for the dehydrogenation of cycloalkanes over a monometallic nickel catalyst [18,24]. The main by-products are methane and benzene, which is indicative of the competing dealkylation of MCH with increasing temperature.…”