煤和焦炭都可以气化而变成含氫和一氧化碳的气体,这就是所謂“水煤气”。用水煤气做为原料,可以來制造合成汽油。合成汽油和天然汽油一样,主要是碳氫化合物(也叫做“烴”)的混合物,不过它的成分不完全和天然汽油相同。由于它含有較多的直鏈結構(直鏈就是不分支鏈的碳氫化合物,如正已烷CH_3—CH_2—CH_2—CH_2—CH_2—CH_3),作为汽車的內燃机的燃料还有一定的缺点:在高速度的时候要發生爆震現象。因此它特別不适合作为飞机燃料。 1936年,苏联科学家莫尔达夫斯基發現,直鏈飽和烴可以环化成为芳香族烴,这个过程就是所謂“芳烴化”。从此以后,各国都在这个方面做了不少工作。这个过程一般用氧化鉻和氧化鋁,氧化钼和氧化鋁做催化剂,反应溫度大約在500℃左右,可以把含有六个、七个、八个碳原子的直鏈飽和烴环化成为芳香烴。这些芳香烴包括苯、甲苯、二甲苯、它們都是防止汽油在汽缸中爆震的有效成分;它们也是有机化学工業中很重要的原料,用它們可以 Both coal and coke can be gasified into gas containing hydrogen and carbon monoxide. This is called “water gas.” Using water gas as a raw material, synthetic gasoline can be produced. Synthetic gasoline, like natural gas, is mainly a mixture of hydrocarbons (also called “hydrocarbons”), but its composition is not exactly the same as that of natural gasoline. Because it contains more straight-chain structures (straight chain is unbranched hydrocarbons, such as n-hexane CH_3-CH_2-CH_2-CH_2-CH_2-CH_3), it has certain disadvantages as a fuel for internal combustion engines of automobiles: Knocking occurs at high speeds. Therefore it is not particularly suitable as an airplane fuel. In 1936, Soviet scientist Mordavsky discovered that straight-chain saturated hydrocarbons can be cyclized into aromatic hydrocarbons. This process is called “aromatization.” Since then, all countries have done a lot of work in this area. This process generally uses chromium oxide and alumina, molybdenum oxide and alumina as catalysts. The reaction temperature is about 500°C, and the linear saturated hydrocarbons containing six, seven, and eight carbon atoms can be cyclized into aromatic hydrocarbons. These aromatic hydrocarbons include benzene, toluene, and xylene, both of which are active components that prevent gasoline from detonating in the cylinder; they are also important raw materials in the organic chemical industry.