Study On Hydrogen Production From Landfill Leachate By Catalytic Supercritical Water Gasification

With the depletion of traditional energy sources and the worsening of environmental pollution,more and more attention has been paid to clean energy.Hydrogen as a new energy representative,is a non-polluting secondary energy,the previous hydrogen production methods have serious waste of resources or irreversible environmental pollution.Supercritical water gasification of hydrogen is the use of supercritical water as a reaction medium for steam reforming,organic matter cracking and a series of reactions to produce hydrogen.The process of hydrogen production from supercritical water gasification not only produces hydrogen,but also the organic matter in landfill leachate degradation,is an environmentally friendly new energy generation.Based on the current international research on hydrogen production from supercritical water gasification,it is possible to produce hydrogen from landfill leachate by using supercritical water gasification.Landfill leachate containing high salt,high nitrogen and a large number of difficult to degrade toxic and harmful organic matter,is one of the difficult to deal with wastewater,in this way both to get new energy can also experiment with the wastewater treatment.This paper mainly discusses the factors that affect the hydrogen production.Factors affecting the leachate feed concentration,catalyst,catalyst loading,temperature,pressure and residence time.As the landfill leachate COD concentration increased from 1660 to 40247 mg/L,the hydrogen yield decreased from 57.22%to36.63%.Although the hydrogen production rate has declined,but the gas production increased the hydrogen production also increased significantly,from 277.4ml rose to563.0ml.After the research shows that using landfill leachate as raw material,compare NaOH,KOH,Na₂CO₃ and K₂CO₃ four kinds of alkali catalyst,NaOH catalytic hydrogen production best,when the NaOH dosage is 5g,the highest yield of 56.40%,also most conducive to the removal of organic matter.The amount of catalyst has a greater impact on hydrogen production,but little effect on the degradation rate of organic matter.As the temperature increased from 380°C to 480°C,the gas production per unit organic matter after addition of the catalyst rose from 132.98 mL to 810.91mL,and the hydrogen production rose from 99.71 mL to 333.85 mL.During the pressure increase process,the hydrogen production per unit of organic matter was increased first and then decreased after adding the catalyst,from 189.83 mL to 342.12mL,andcontinuing to increase pressure,hydrogen production fell to 232.20 mL.The COD removal rate decreased from 81.66%to 56.78%.The increase of pressure was unfavorable to the generation of hydrogen and the degradation of organic matter.When the residence time extended from 5min to 20min,the yield of hydrogen did not change much,at 45±5%,the degradation rate of organic matter increased slightly,from 51.42%to 62.11%.The results have little effect.The results of range analysis by orthogonal experiment showed that the effect on the reaction results was as follows:temperature>amount of catalyst>pressure,and found that the higher the temperature and the lower the pressure,the better the hydrogen production.By using GC-MS to test the liquid before and after the reaction for mechanism,it is found that all four catalysts had a certain catalytic effect,but the most outstanding one was NaOH.The peak area after two minutes reached 69.67%.the peak area of two minutes to reach 64.98%and 46.02%by using Na₂CO₃ and K₂CO₃,Although KOH has the worst catalytic effect,the peak area can reach 62.94%in six minutes.At the end of this paper,effect of four kinds of catalysts was used to study the kinetics of the reaction results,and a kinetic model was established.