Reducing priority polycyclic aromatic hydrocarbons in coal tar pitch through alkylation: Mechanism and potential
Na Zhang1, Lei-Qiang Liu2, Yao Zhang1
1College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Shanxi 030024, China.
Abstract:
Coal tar pitch (CTP) is a carbon material with abundant yield in China, but the toxic polycyclic aromatic hydrocarbons (PAHs) contained in it have restricted its broader applications. In order to reduce the PAHs content, an alkylation method was developed in this study to modify CTP (MCTP) by using 1-dodecene as the alkylating reagent, and the optimal reaction conditions (temperature 170 °C, time 4 h, solvent dosage 60 times that of CTP, and alkylating reagent dosage 4 times that of CTP) for synthesizing the MCTP were determined by alkylation modification with model compounds. Compared with CTP, the content of PAHs in MCTP was reduced by 97.35 %. The mechanism of the reaction was explained by analyzing the types of alkylation products and combining structural analyses of CTP and MCTP. PAHs emissions from fumes and the toxic equivalent quantity (TEQ) among different environmental standards were greatly reduced, while MCTP demonstrated low cytotoxicity and ecotoxicity. The method can also be applied to the toxicity assessment of road materials such as alkylation by-products.
More Related Videos
09:46Reducing Willow Wood Fuel Emission by Low Temperature Microwave Assisted Hydrothermal Carbonization
Published on: May 19, 2019
12:08Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes
Published on: June 24, 2022
Related Concept Videos
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
01:19Phase I Reactions: Oxidation of Aliphatic and Aromatic Carbon-Containing Systems
Oxidation reactions are fundamental in aromatic carbon-containing systems. An example is the hydroxylation of phenobarbital, a process that transforms it into...
02:13Reduction of Alkenes: Catalytic Hydrogenation
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
02:27Preparation of Alkynes: Alkylation Reaction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
01:25Aromatic Compounds: Overview
In 1825, Faraday...
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.