Effects of the Carbon Support Doping with Nitrogen for the Hydrogen Production from Formic Acid over Ni Catalysts

Alina D Nishchakova,Lyubov G Bulusheva,Igor P Asanov,Arcady V Ishchenko,Dmitri A Bulushev,Olga A Stonkus,Alexander V Okotrub

doi:10.3390/en12214111

Abstract

Porous nitrogen-doped and nitrogen-free carbon materials possessing high specific surface areas (400–1000 m2 g−1) were used for deposition of Ni by impregnation with nickel acetate followed by reduction. The nitrogen-doped materials synthesized by decomposition of acetonitrile at 973, 1073, and 1173 K did not differ much in the total content of incorporated nitrogen (4–5 at%), but differed in the ratio of the chemical forms of nitrogen. An X-ray photoelectron spectroscopy study showed that the rise in the synthesis temperature led to a strong growth of the content of graphitic nitrogen on the support accompanied by a reduction of the content of pyrrolic nitrogen. The content of pyridinic nitrogen did not change significantly. The prepared nickel catalysts supported on nitrogen-doped carbons showed by a factor of up to two higher conversion of formic acid as compared to that of the nickel catalyst supported on the nitrogen-free carbon. This was related to stabilization of Ni in the state of single Ni2+ cations or a few atoms clusters by the pyridinic nitrogen sites. The nitrogen-doped nickel catalysts possessed a high stability in the reaction at least within 5 h and a high selectivity to hydrogen (97%).

Highlights

Hydrogen is one of the most promising substances that can replace usable sources of energy like natural gas or oil because it is ecologically pure and can be produced from renewable sources
A quick thermolysis of calcium tartrate accompanying by release of CO2 and H2 O gases results in the formation of highly dispersed CaO particles [23]. These particles serve as a template for the growth of graphene-like layers catalyzed by iron incorporated into the template
Time-on-stream, min Nitrogen-doping of the carbon support led to a significant increase of the rate of the hydrogen production from formic acid decomposition

Summary

Introduction

Hydrogen is one of the most promising substances that can replace usable sources of energy like natural gas or oil because it is ecologically pure and can be produced from renewable sources. Hydrogen usage has difficulties associated with its storage and transportation. That is why hydrogen production from different organic compounds with a relatively high content of hydrogen is a current trend in catalysis. Formic acid is a liquid organic hydrogen carrier containing. 4.4 wt% of hydrogen, which can be liberated relatively easy using some catalysts. It is important that formic acid can be produced from biomass or CO2 [1,2]. The most efficient catalysts for the hydrogen production from formic acid are based on palladium

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