Production of COx-Free Hydrogen and Few-Layer Graphene Nanoplatelets by Catalytic Decomposition of Methane over Ni-Lignin-Derived Nanoparticles.

Qiangu Yan,Timothy Ketelboeter,Zhiyong Cai

doi:10.3390/molecules27020503

Abstract

Nickel (Ni)-lignin nanocomposites were synthesized from nickel nitrate and kraft lignin then catalytically graphitized to few-layer graphene-encapsulated nickel nanoparticles (Ni@G). Ni@G nanoparticles were used for catalytic decomposition of methane (CDM) to produce COx-free hydrogen and graphene nanoplatelets. Ni@G showed high catalytic activity for methane decomposition at temperatures of 800 to 900 °C and exhibited long-term stability of 600 min time-on-stream (TOS) without apparent deactivation. The catalytic stability may be attributed to the nickel dispersion in the Ni@G sample. During the CDM reaction process, graphene shells over Ni@G nanoparticles were cracked and peeled off the nickel cores at high temperature. Both the exposed nickel nanoparticles and the cracked graphene shells may participate the CDM reaction, making Ni@G samples highly active for CDM reaction. The vacancy defects and edges in the cracked graphene shells serve as the active sites for methane decomposition. The edges are continuously regenerated by methane molecules through CDM reaction.

Highlights

Hydrogen proton-exchange membrane fuel cells (H2 -PEMFCs) are promising energy conversion devices for electric vehicles and portable appliances
Ni-lignin composites were prepared using the coprecipitation method catalytically graphitized to few-layer graphene-encapsulated nickel nanoparticles (Ni@G). These Ni@G nanoparticles were used for catalytic decomposition of methane (CDM) to produce COx-free hydrogen and graphene nanoplatelets
Ni-lignin nanocomposites were prepared from nickel nitrate and kraft lignin

Summary

Introduction

Hydrogen proton-exchange membrane fuel cells (H2 -PEMFCs) are promising energy conversion devices for electric vehicles and portable appliances. The platinum catalysts in the electrodes of PEMFCs are poisoned by trace amounts of carbon monoxide (CO) in the hydrogen. Only high purity (100 ppm or less of CO). Hydrogen is desired for use in H2 -PEMFC devices [1]. More than 50% of hydrogen is presently produced from steam reforming of natural gas, which simultaneously generates. COx (CO and CO2 ) must be removed through a series of purification processes before obtaining high purity hydrogen [2]. The water-gas shift reaction (WGSR) is performed to convert CO to CO2 over a catalyst (usually an iron oxide catalyst) (Equation (2)): Licensee MDPI, Basel, Switzerland

Methods

Results

Conclusion