2. Sulfuric acid can purify petroleum, because alkanes in petroleum are insoluble in sulfuric acid and do not react with concentrated sulfuric acid, while alkenes can react with concentrated sulfuric acid to generate bisulfate, so the mixture of alkanes and alkenes is usually washed with cold concentrated sulfuric acid to remove alkenes mixed in alkanes. The price of sulfuric acid is positively related to the price of oil.
3. The upstream of dye industry is petrochemical industry, and the downstream is textile printing and dyeing industry. The upstream of dye industry chain is petrochemical industry, coal chemical industry and basic chemical industry, in which petrochemical industry provides raw materials such as benzene and aromatic derivatives, coal chemical industry provides important raw materials such as coal tar, and basic chemical industry provides inorganic raw materials such as soda ash and nitric acid.