On Removal Pathway Of Specific Nitrogen Compounds From Algae Bio-crude

The development and utilization of renewable energetic resourses have been a worldwide common concern due to the energy crisis and environmental problems.Amongst various countmeasures,algae hydrothermal liquefaction is considered a promising energetic production method in form of bio-crude.However,some components of the crude meterials are converted into nitrogen substances,such as pyrrole,quinoline,indole and amines in this process,leading to high risk of NO_X emissions when directly used to supply energy.Therefore,nitrogen removal becomes a necessary process before biocrude is used as alternative energy or chemical raw material.At present,the methods of nitrogen removal fall into chemical and physical ones,both of prospect.The non-hydrogenation cracking in the first category features with relatively simple and easily controlable reaction process,while adsorptive denitrogenation in the second works efficiently under mild conditions.For sake of briefing research and avoiding unnecessary disturbances,typical and and specific itrogen compounds are used as researching material in the comparative study of both pathways,in hope of basic infomation to facilitate decision-making among feasible process stradegies.Cracking experiments produce mostly low carbon unsaturated hydrocarbons at the temperature as high as 800 ~oC by releasing nitrogen in form of elementary substance.ZSM-5 molecular sieve can effectively lower the catalytic cracking temperature of pyrrole to about 500 ~oC with the similar productive profile.However,quinoline and indole are not satisfactorily cracked even under catalysis,which eclipses the prospect of this denitrification option.A formula oil as the object of study was prepared before adsorptive investigations by mixing specific components like non-heterocyclic aniline,basic heterocyclic quinoline,non-basic heterocyclic indole,and actane.The following work includes effects of layered double hydroxide(LDHs)on the adsorptive denitrogenation,of three factors,namely adsorption time,temperature,the quality ratio of adsorbent to oil(A/O).Total adsorption capacity of LDHs hit 325.7 mg/g when the adsorption lasts 90 min at the temperature of 20 ~oC,and A/O 1:80,with the adsorption capacity of quinoline touching 216.3 mg/g.The adsorptive capability stabilizes after 4 rounds regenerations.The adsorption performance of different physicochemical properties adsorbents,are possibly be improved through multilateral interaction under the suspended state in the solution.For this reason the following work focused on the optimization of adsorpyive denitrification through combined adsorbents.Among the options,LDHs+silica gel show the best adsorption performance under adsorption time 90 min,temperature 20 ~oC and A/O 1:100),followed by active carbon+silica gel(the same adsorption time,temperature 60 ~oC and A/O 1:80).These adsorbents reach stable adsorption performance after 4 regenerating by ethanol.