Studies On Preparation,Modification And Storage Hydrogen Of High-Surface-Area Activated Carbon

Contradiction between energy consumption and supply emerged to be the mostimportant factor affecting the world economy and peace. One side is the acceleratedincrease in energy requirement following the fast increase in population and economysize of the world;the other side is the insufficient energy production following the nearerand nearer depletion of resources on the earth. World environment is also getting worsedue to burning more and more fossil fuels. Therefore, searching for alternative fuels is anurgent task of human society. Most important consideration in the search is whether thealternative fuel is clean and renewable. Hydrogen is a candidate that satisfies bothconstraints;therefore, hydrogen energy has been talking by more and more people.However, hydrogen storage is a bottleneck of utilizing the energy. No one method of thestorage technologies available today meets the criterion of the Department of Energy,USA. Carbon material is already a candidate of hydrogen carrier. It has low specificweight and can reach very high specific surface area with reasonable cost. Hydrogencharging and discharging is reversible, and the storage is costly competitive. In this article,physically activation and the combination of physically and chemically activation areused to make a series of activated carbon, the influences of preparation and modificationconditions on the pore structure and hydrogen storage are studied.In chemically activation , the ratios of KOH to precursor had a great effect onactivated carbon. The results showed the optimistic ratio was 4:1. Mixture method,activation temperature, activation sequence and granularity also effected the properties ofactivated carbon. The results showed the mechanically physically mixture was better thandissolution mixture, the optimistic temperature was 850℃, physical after chemicalsequence preceded chemical after physical sequence. The choice of granularity hadaffinity with the choice of the ratios of KOH to precursor, when the ratio of KOH toprecursor was higher, the granularity needed smaller;when the ratio of KOH to precursorwas lower, the granularity needed larger.In an attempt to enhance the hydrogen adsorption capability, physically activatedcarbons are modified by two methods: pre-adsorption and impregnation. The resultsshowed that the pre-adsorption treatment could not enhance the hydrogen uptake ofactivated carbon. The treatment of the activated carbon with ammonia solution andhydrofluoric acid increased the hydrogen uptake for 3.6 % and 5.5 % at 9.5 MPa,respectively. However, treating the carbon with phosphoric acid decreased the hydrogenuptake for 18.0 % at 9.5MPa, while treating the carbon with nitric acid almost didn'tchange hydrogen uptake quantity.In order to improve the bulk density of activated carbon, we pelleted it .The bindingused is PTFE, the optimistic experimental condition was: the ratio of binding to activatedcarbon was1:83.3 at ambient temperature and 10MPa. The result showed that the bulkdensity enhanced 82%, however, specific surface area only decreased 5.7%.