Gaseous Products Hydrogen Research Articles

Biological Processes for Hydrogen Production.

Methane is produced usually from organic waste in a straightforward anaerobic digestion process. However, hydrogen production is technically more challenging as more stages are needed to convert all biomass to hydrogen because of thermodynamic constraints. Nevertheless, the benefit of hydrogen is that it can be produced, both biologically and thermochemically, in more than one way from either organic compounds or water. Research in biological hydrogen production is booming, as reflected by the myriad of recently published reviews on the topic. This overview is written from the perspective of how to transfer as much energy as possible from the feedstock into the gaseous products hydrogen, and to a lesser extent, methane. The status and remaining challenges of all the biological processes are concisely discussed.

Biofuels from algae for sustainable development

Microalgae are photosynthetic microorganisms that can produce lipids, proteins and carbohydrates in large amounts over short periods of time. These products can be processed into both biofuels and useful chemicals. Two algae samples ( Cladophora fracta and Chlorella protothecoid) were studied for biofuel production. Microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels. Microalgae can be converted to biodiesel, bioethanol, bio-oil, biohydrogen and biomethane via thermochemical and biochemical methods. Industrial reactors for algal culture are open ponds, photobioreactors and closed systems. Algae can be grown almost anywhere, even on sewage or salt water, and does not require fertile land or food crops, and processing requires less energy than the algae provides. Microalgae have much faster growth-rates than terrestrial crops. the per unit area yield of oil from algae is estimated to be from 20,000 to 80,000 liters per acre, per year; this is 7–31 times greater than the next best crop, palm oil. Algal oil can be used to make biodiesel for cars, trucks, and airplanes. The lipid and fatty acid contents of microalgae vary in accordance with culture conditions. The effect of temperature on the yield of hydrogen from two algae ( C. fracta and C. protothecoid) by pyrolysis and steam gasification were investigated in this study. In each run, the main components of the gas phase were CO 2, CO, H 2, and CH 4.The yields of hydrogen by pyrolysis and steam gasification processes of the samples increased with temperature. The yields of gaseous products from the samples of C. fracta and C. protothecoides increased from 8.2% to 39.2% and 9.5% to 40.6% by volume, respectively, while the final pyrolysis temperature was increased from 575 to 925 K. The percent of hydrogen in gaseous products from the samples of C. fracta and C. protothecoides increased from 25.8% to 44.4% and 27.6% to 48.7% by volume, respectively, while the final pyrolysis temperature was increased from 650 to 925 K. The percent of hydrogen in gaseous products from the samples of C. fracta and C. protothecoides increased from 26.3% to 54.7% and 28.1% to 57.6% by volume, respectively, while the final gasification temperature was increased from 825 to 1225 K. In general, algae gaseous products are higher quality than gaseous products from mosses.

Hydrogen from Mosses and Algae via Pyrolysis and Steam Gasification

In this study, the effect of temperature on the yield of hydrogen from two mosses (Polytrichum commune and Thuidium tamarascinum) and two algae (Cladophora fracta and Chlorella protothecoid) by pyrolysis and steam gasification were investigated. In each run, the main components of the gas phase were CO2, CO, H2, and CH4. The yields of hydrogen by pyrolysis and steam gasification processes of the samples increased with temperature. The yields of gaseous products from the samples of Polytrichum commune, Thuidium tamarascinum, Cladophora fracta, and Chlorella protothecoides increased from 5.3 to 40.6%, 6.5 to 42.2%, 8.2 to 39.2%, and 9.5 to 40.6% by volume, respectively, while the final pyrolysis temperature was increased from 575 to 925 K. The percent of hydrogen in gaseous products from the samples of Polytrichum commune, Thuidium tamarascinum, Cladophora fracta, and Chlorella protothecoides increased from 21.3 to 38.7%, 23.0 to 41.3%, 25.8 to 44.4%, and 27.6 to 48.7% by volume, respectively, while the final pyrolysis temperature was increased from 650 to 875 K. The percent of hydrogen in gaseous products from the samples of Polytrichum commune, Thuidium tamarascinum, Cladophora fracta, and Chlorella protothecoides increased from 21.8 to 50.0%, 23.5 to 52.0%, 26.3 to 54.7%, and 28.1 to 57.6% by volume, respectively, while the final gasification temperature was increased from 825 to 1,225 K.

Hydrogen-rich Gases from Biomass via Pyrolysis and Air-steam Gasification

In this work, the yields of hydrogen-rich gases via pyrolysis and air-steam gasification processes were investigated at different temperature ranges. In each run, the main components of the gas phase were CO2, CO, H2, and CH4. The yields of hydrogen from the pyrolysis and the air-steam gasification increase with increasing of temperature. In general, the gasification temperature is higher than that of pyrolysis and the yield of hydrogen from the gasification is higher than that of the pyrolysis. The percent of hydrogen in gaseous products by pyrolysis from the samples of hazelnut shell, tea waste, and spruce wood increased from 36.8 to 43.5%, 41.0 to 53.9%, and 40.0 to 51.5% by volume, respectively, while the final pyrolysis temperature was increased from 700 to 950 K, and the percent of hydrogen in gaseous products by air-steam gasification from the samples of hazelnut shell, tea waste, and spruce wood increased from 43.3 to 56.9%, 41.0 to 53.9%, and 40.0 to 51.5% by volume, respectively, while the final air-gasification temperature was increased from 900 to 1,250 K.

Thermochemical Conversion of Mosses and Algae to Gaseous Products

The effect of temperature on the yield of hydrogen from two mosses (Polytrichum commune and Thuidium tamarascinum) and two algae (Cladophora fracta and Chlorella protothecoid) by pyrolysis and steam gasification were investigated in this study. In each run, the main components of the gas phase were CO2, CO, H2, and CH4. The yields of hydrogen by pyrolysis and steam gasification processes of the samples increased with temperature. The yields of gaseous products from the samples of Polytrichum commune, Thuidium tamarascinum, Cladophora fracta, and Chlorella protothecoides increased from 5.3 to 40.6%, 6.5 to 42.2%, 8.2 to 39.2%, and 9.5 to 40.6% by volume, respectively, while the final pyrolysis temperature was increased from 575 to 925 K. The percent of hydrogen in gaseous products from the samples of Polytrichum commune, Thuidium tamarascinum, Cladophora fracta, and Chlorella protothecoides increased from 21.3 to 38.7%, 23.0 to 41.3%, 25.8 to 44.4%, and 27.6 to 48.7% by volume, respectively, while the final pyrolysis temperature was increased from 650 to 925 K. The percent of hydrogen in gaseous products from the samples of Polytrichum commune, Thuidium tamarascinum, Cladophora fracta, and Chlorella protothecoides increased from 21.8 to 50.0%, 23.5 to 52.0%, 26.3 to 54.7%, and 28.1 to 57.6% by volume, respectively, while the final gasification temperature was increased from 825 to 1,225 K. In general, algae gaseous products are higher quality than gaseous products from mosses.

Hydrogen from Biomass via Pyrolysis: Relationships between Yield of Hydrogen and Temperature

Hydrogen is a sustainable, non-polluting source of energy that can be used in mobile and stationary applications. The use of hydrogen as an energy carrier or major fuel requires development in several industry segments including production, delivery, storage, conversion, and end-use. It is an obvious alternative to hydrocarbon fuels such as gasoline. Hydrogen can be produced through thermal, electrolytic, or photolytic processes applied to fossil fuels, biomass, or water. The yields of gaseous products from pyrolysis runs of the biomass samples increase with increasing pyrolysis temperature. The yield of hydrogen in gaseous products from the samples of hazelnut shell, cotton cocoon shell, tea factory waste, olive husk, beech wood and spruce wood increased from 34.0 to 54.8%, 22.1 to 41.0%, 28.9 to 47.8%, 36.0 to 50.6%, 31.5 to 48.3%, and 33.2 to 49.6%, respectively, while the final pyrolysis temperature increased from 650 to 1025 K. There is a relationship between the yield of hydrogen in a gaseous product from the biomass sample and pyrolysis temperature. The yield of hydrogen is a linear function of the pyrolysis temperature.

Interaction of hydrogen atoms with coadsorbed D/CH3I adlayers on Ni (100) surfaces: Evidence for hot atom mediated reactions

Adlayers of coadsorbed hydrogen (deuterium) atoms and methyliodide, H/CH3I, D/CH3I, H/CD3I, D/CD3I, were prepared on Ni(100) surfaces by adsorption of methyliodide on hydrogen (deuterium) saturated surfaces at 120 K. Upon directing thermal D (H) atoms at these adlayers as gaseous products hydrogen and methane molecules were observed which constitute of surface species only, e.g., H2 and CH4 in the combination: D→H/CH3I. The rates of formation of these products give evidence for reaction mechanisms in which adsorbed atoms, e.g., H, activated by collisions with incoming atoms, e.g., D, react with surface species, either H or CH3I to form H2 and CH4. The reaction cross sections and isotope effects in H→D/CD(H)3I or D→H/CH(D)3I reactions support a collision model in which hot atoms act as mediators in the reaction pathways.