Positive Material Identification

In this post, I'll inform you about Materials Characterization using Positive Material Identification. This Post is related to one of my subject in my master course namely "Materials Characterization".
Notes: The explanation will be in Bahasa Indonesia. Enjoy :)


Positive Material Identification

Carbon Active as Hydrogen Storage

Carbon Active as Hydrogen Storage is a general topic of my thesis. The purpose of this research is referring to provide a good storage for hydrogen which is used as an unlimited fuel. Hydrogen is oxidized cleanly to water  when combustion process, at the same time if we use the fuel in general there are elements of C that can produce CO. Hydrogen has the highest energy to weight ratio (120kJ/g) of any fuel. Hydrogen is the ideal fuel for fuel cells and can also be used in an internal combustion engine. There are two important things that need attention, there are hydrogen production and hydrogen storage. For hydrogen production, over 500 billion m³ per year of hydrogen generated globally. Over 90% of hydrogen produced from fossil fuels, 48% from steam reforming of natural gas, 30% from oil and off-gases of refineries and chemical plants, 18% form gasification of coal, 4% from electrolysis. For hydrogen storage there are several options to storage the hydrogen such as gaseous hydrogen stored under high pressures, liquid hydrogen, as a hyride(metal, complex,chemical), gas on solid adsorption (carbon nanotubes, inorganic nanotubes, metal organic frameworks or porous materials^.[1] Among them, porous carbon materials as on of the hydrogen storage types consider the best advantages which is light weight, fast kinetics, complete reversibility, low cost, and high surface area. With high surface area, high micropore volume,appropriate tailoring pore structures and texture of the carbon material then hydrogen storage capacity will be increase. There are several new techniques to storage hydrogen such as template carbonization and carbide derived car techniques but both of them still have disadvantages which make porous carbon material still the best choice to storage hydrogen with simple preparation and long history is is activated carbon. ^[2]

Activated carbon can be defined as carbonaceous material having high porosity and internal surface area and cannot be characterized by any distinctive chemical formula. There are two different process for the preparation of activated carbon, they called physical and chemical activation. In physical activation involves of carbonization of carbonaceous precursor which is followed by gasification of the resulting char or direct activation of the starting material in the presence of an activating agent such as CO₂, steam or both. This process eliminiates selectively the most reactive carbon atoms of the structure generating the porosity. In chemical reactivation, the precursor is impregnated with a given chemical agent and then is pyrolyzed which is much richer carbon content material with a much more ordered structure is produced and when the chemical agents is eliminated by heat treatment the porosity will highly developed. With chemical activation we can get so much advantages such as we use lower temperature and shorter time than those used in physical activation, we can get high surface area activated carbon, the yield of carbon is higher than physical activation which is caused by the chemical agents used are substances with dehydrogenation properties that inhibit formation of tar and reduce the production of other volatile products.^[3]  

In my research, I'm gonna use mechanochemical method which is a combination of chemical activation method with KOH as activating agents and mechanical process. In this method, not only activating agents play an important role but also ball mill too. Activated coal will be mixed with activating agents in planetary ball mill. After that, a mixture of activated coal and activating agents will be pelleted and heat treated. And the last step is characterization the material. With this method, we're hoping that the hydrogen storage capacity will be increased. 
Different with my previous post where i said I'm gonna use activated carbons from coal and coconut shell as a material, now i am only using activated carbons from coal.

About the details of my thesis, i still discuss it with my thesis supervisor and do a literature study to find the best variable for this research. So I will inform you soon when there is something new. :)

 

Reference:

1. Associate Professor Craig Buckley. The Hydrogen Economy – Hydorgen Storage Options. Australia: Department of Imaging and Applied Physics, Curtin University

2. Wang, Huanlei, Qiuming Gao, ^*Juan Hu.2009. High Hydrogen Storage Capacity of Porous Carbons Prepared by Using Activated Carbon. China

3.    Lozano-Castello,D., M.A. Lillo-Ro´denas, D. Cazorla-Amoro´s, A. Linares-Solano*.2000. Preparation of activated carbons from Spanish anthracite I. Activation by KOH. Spain: Departamento de Quitmica Inorganica, Universidad de Alicante