William Tongamp

Generation of hydrogen from polyvinyl chloride by milling and heating with CaO and Ni(OH)2

This work discusses an alternative process option for the treatment of polyvinyl chloride (PVC) by producing hydrogen (H(2)) gas, at the same time fixing chlorine for proper environmental control. In the first-stage, a milling operation is performed in a planetary ball mill to obtain a mixture of PVC sample with CaO and Ni(OH)(2) to be used as feed in the second-step, involving heating of the milled product. Analyses by thermogravimetry-mass spectroscopy (TG-MS) and gas chromatography (GC) showed H(2), CH(4), CO and CO(2) as main constituents. The results clearly show that addition of Ni(OH)(2) to provide nickel as catalyst and CaO as adsorbent to fix CO(2) and HCl gases generated during heating, assisted in clean H(2) generation with concentration near 90% at temperatures between 450 and 550 degrees C. Analyses of solids after heating by X-ray diffraction and TG-DTA techniques showed both CaOHCl and CaCO(3) as main phases in the product. This process could be developed to treat PVC wastes together with other polymers and/or plastic wastes for production of H(2) gas.

Generation of high-purity hydrogen from cellulose by its mechanochemical treatment

Cellulose was mixed with the hydroxides of lithium and nickel and the mixture was milled, followed by heating to produce hydrogen. Several analytical methods of X-ray diffraction (XRD), thermogravimetry/mass spectrometry (TG/MS) and gas chromatography (GC) were used to characterize the samples. Hydrogen was emitted when heating the milled sample around 400 degrees C together with low concentrations of methane, carbon monoxide and carbon dioxide. It is understood that an interaction occurs between cellulose and lithium hydroxide to convert the carbon of cellulose into lithium carbonate and to emit hydrogen correspondingly. It is also found that nickel catalyst is required to facilitate the interaction and the behaviours of three different nickel compounds were compared. When high yield of hydrogen emission is available, the prepared samples can also serve the purpose of hydrogen storage.

A Mechanochemical Approach to Generate Hydrogen for Cellulose

Cellulose [C6(H20)5] was co-ground with calcium (Ca(OH)2) and nickel (Ni(OH)2) hydroxides, followed by heating the ground samples up to 1000 °C for determination of temperature range at which hydrogen (H2) gas can be generated. The results showed that the main gaseous products were; H2, CH4, H 2 0 , CO, and C 0 2 with H2 as the dominant gas generated between 350 and 550 °C. Analyses of the gaseous products by T G MS and gas-chromatography, and solid products by TG-DTA and XRD showed that C 0 2 gas was fixed as CaC0 3 at temperatures between 350 to 600 °C allowing generation of H2 gas with concentrations ranging from 90 to 99% with carbon oxide (CO, C 0 2 ) concentrations less than 1%. A plausible reaction mechanism is attributed to the interaction between cellulose and Ca(OH)2 to transform the carbon in cellulose into CaC0 3 , to which nickel works as catalyst. Accompanying the carbonate formation reaction, H2 emission occurs correspondingly. This process offers a new approach to produce H2 gas from the renewable biomass sources.