What are the main impurities in cylinder hydrogen?

We are a manufacturer that produces polypropylene using the small-body method. In the past, pure chlorine was used, which was more expensive. Now we want to switch to hydrogen, but we are not sure if there are any problems. Please give advice from colleagues!

Brother, are you talking about hydrogen, not chlorine? There are many processes for producing hydrogen, and different regions use different methods. Hydrogen around refineries and chemical plants is generally PSA hydrogen purification process, continuous reforming hydrogen production, natural gas * (coke dry) and other fuel gas to produce hydrogen. Other situations include hydrogen production by methanol oxidative reforming, ammonia decomposition, water electrolysis, solar hydrogen production, seaweed hydrogen production, methanol-steam reforming (MSR) hydrogen production, biomass gasification and microbial catalytic dehydrogenation, etc. The usual principles are: 1. The electrolysis of water for hydrogen production usually uses a series electrolytic cell (shaped like a filter press) with iron as the cathode side and nickel as the anode side to electrolyze the aqueous solution of caustic potassium or caustic soda. Oxygen comes out of the anode and hydrogen comes out of the cathode. This method is more expensive, but the product has high purity and can directly produce hydrogen with a purity of more than 99.7%. Hydrogen of this purity is commonly available: ①Reducing agent, protective gas and heat treatment of permalloy used in the electronics, instrument and meter industries, ② reducing agent used in the production of tungsten, molybdenum, cemented carbide, etc. in the powder metallurgy industry, ③ production of polysilicon, germanium and other semiconductor raw materials, ④ hydrogenation of grease, ⑤ cooling gas in dual hydrogen internal cooling generators, etc. For example, the Beijing Electronic Tube Factory and the Gas Factory of the Academy of Sciences produce hydrogen through water electrolysis. 　　2. Hydrogen production by water gas method uses anthracite or coke as raw material and reacts with water vapor at high temperature to obtain water gas (C+H2O→CO+H2—heat). After purification, it is then passed through a catalyst with water vapor to convert the CO into CO2 (CO+H2O→CO2+H2) to obtain a gas with a hydrogen content of more than 80%. The gas is then pressed into water to dissolve the CO2, and then the remaining CO is removed through ammonia-containing copper formate (or ammonia-containing copper acetate) solution to obtain purer hydrogen. This method of hydrogen production has low cost, large output, and more equipment. This method is often used in synthetic ammonia plants. Some also synthesize methanol from CO and H2, and a few places use less pure gas with 80% hydrogen for artificial liquid fuel. This method is often used by Beijing Chemical Experimental Plant and small nitrogen fertilizer plants in many places. 　　3. Hydrogen production from synthetic gas and natural gas produced by thermal cracking of petroleum. The hydrogen production by-product of thermal cracking of petroleum is very large. It is often used for hydrogenation of gasoline, hydrogen required for petrochemical and fertilizer plants. This method of hydrogen production is used in many countries around the world. * * This method is used to produce hydrogen in my country's petrochemical bases such as the Zaiqing Fertilizer Plant and the petrochemical base of the Bohai Oilfield. It is also used in some places (such as the Bay, Way and Batan Rougo hydrogenation plants in the United States). 　　4. Coke oven gas refrigeration and hydrogen production freeze and pressurize the initially purified coke oven gas to liquefy other gases and leave hydrogen. This method is used in a few places (such as the Ke Mepobo factory in the former Soviet Union). 　　5. Hydrogen is a by-product of the electrolysis of salt water. In the chlor-alkali industry, a large amount of relatively pure hydrogen is a by-product. In addition to being used for the synthesis of hydrochloric acid, there is a surplus that can also be purified to produce ordinary hydrogen or pure hydrogen. For example, the hydrogen used in the Second Chemical Plant is a by-product of electrolyzed brine. 　　6. When fermenting propylene and butanol from corn by-products in the brewing industry, more than 1/3 of the hydrogen is contained in the waste gas of the fermentation tank. After multiple purifications, ordinary hydrogen (more than 97%) can be produced. The ordinary hydrogen is cooled to -10 by using liquid nitrogen. In silica gel tubes below 0°C, impurities (such as a small amount of N2) can be further removed to produce pure hydrogen (more than 99.99%). Beijing Brewery produces this by-product hydrogen, which is used to bake quartz products and supply to external units. 　　7. The reaction of iron and water vapor produces hydrogen, but the quality is poor. This older method has been basically eliminated. As for the impurities you mentioned, I'm not sure.

Nowadays, two-stage PSA can be used to produce 99.999% electronic-grade high-purity hydrogen with pitifully low impurities. 99.9% pure hydrogen requires only primary PSA, and the main impurities are safe N2. The price of the former is much higher.

I am most worried about CO, which will affect the reaction even in trace amounts.

Manufacturers that produce polypropylene using the small-bulk method use very little hydrogen and can just use electrolytic hydrogen. If you have a source of hydrogen, you can install a small PSA to produce the high-purity hydrogen you need.