Petroleum - Factors Affecting the Cracking of Petroleum

When Professor Silliman made his first examination of the newly-discovered Pennsylvania rock oil in 1859, he noted that different rates of heating produced different results in fractionation—longer heating produced larger percentages of light fractions. In 1862, it was found that when petroleum vapors are condensed in the still crown and dropped back into the hot liquid, the result of the distilling operation is materially modified. These early dates mark the beginning of what is called cracking petroleum and is explained as separating the component parts of the hydrocarbon molecules into more and smaller groups of the same elements. The phenomena were utilized for the next 30 years to increase the yield of burning oil. The procedure was that regularly practiced today in dry or destructive distillation. Considerable scientific study was given to the subject from 1862 to 1905, and a number of patents were obtained, but the work done was not continuous or intensive until about 1905, when the increasing demand for gasoline attracted attention of petroleum refiners to the possibilities of cracking. The first equipment built and operated essentially for cracking petroleum on a large scale was placed in successful operation in 1912. The commercial practice is, therefore, less than 15 years old. Comprehensive intense study of the controlling factors during this period has resulted in rapid increase in our knowledge, and material improvement has been made in the practice of the art. It is the purpose of this paper to outline briefly the state of our knowledge and to suggest some of the questions which are attracting attention of researchers at the present time. The major purposes for which petroleum hydrocarbons, including natural gas, are or have been cracked are: 1. To obtain products used to increase the heat value and illuminant content of artificial gas. 2. During the World War, to increase the supply of toluol. 3. To increase the amount of products capable of conversion into industrial chemicals. 4. To produce pure carbon.