Olefins - Current Technology

Prior to the petrochemical age, ethylene was obtained from coal-gas which was produced by the pyrolysis of coal. Coal pyrolysis was widespread for the production of town gas and is still conducted on a large scale for the production of coke in steel production. 

Technology for the production of coke has been known for many hundreds of years. There are many forms of the process the two main ones are for the production of coke for iron manufacture and for the production of gas and chemicals. 

Carbonization refers to the heating of bituminous coal in ovens or retorts sealed from air to form coke. The process involves thermal decomposition of the coal with distillation of the products. Various technologies are used which perform the process at (i) low temperature (500-750 C), (ii) medium temperature (750-900°C) and 

The coke ovens are held in batteries of many ovens producing coke on a batch basis. A typical coke oven is about 40 ft long, 14ft high 

For the production of town gas, the operation is similar. Carbonization is usually performed at a lower temperature and the ovens are smaller and generally referred to as retorts. 

---

Current technologies for the conversion of methane into gasoline, middle distillate and petrochemicals require initial formation of intermediate feedstocks such as synthesis gas, methanol and lower olefins which in turn must be converted to the desired products. Whilst adding an extra stage such an approach may add flexibility to the overall conversion of methane. For example, the production of lower olefins such as ethylene and propylene from methane has the potential to satisfy needs in the fuels, commodity and speciality chemicals a reas. 

Despite the above drawbacks, metal-peroxo chemistry will have an increasing contribution to clean industrial epoxidations. One of the current technologies used for propylene oxide and epichlorhydrin is the chlorhydrin route, where olefin is reacted with hypochlorous acid (from chlorine) followed by ring-closure of the chlorhydrin with lime ... 

The preceding discussions illustrate that membranes have shown great potential as an alternative for olefin/paraffin separation, yet the performance of current membranes is insufficient for commercial deployment of this technology. Advanced material development is highly desired to improve the membrane properties and reduce cost. Another possible approach involves hybrid membranes with zeolites or CMS incorporated in a continuous polymer phase. More discussion in this regard will be covered later in this chapter. 

There is no doubt that catalytic asymmetric synthesis has a significant advantage over the traditional diastereomeric resolution technology. However, it is important to note that for the asymmetric hydrogenation technology to be commercially useful, a low-cost route to the precursor olefins is just as crucial. The electrocarboxylation of methyl aryl ketone and the dehydration of the substituted lactic acids in Figures 5 and 6 are highly efficient. Excellent yields of the desired products can be achieved in each reaction. These processes are currently under active development. However, since the subjects of electrochemistry and catalytic dehydration are beyond the scope of this article, these reactions will be published later in a separate paper. 

Friedel-Crafts technology and zeolite- or other solid catalyst-based processes are currently used for other aromatic alkylations, in particular for the manufacture of linear alkylbenzenes (LABs) made from C10-C14 olefins (Equation 8), or from the corresponding chloroparaffins and benzene, and also to make m- and p-cymene (isopropyltoluene Equation 9). LABs are used for the production of sulfonate detergents, while cymenes lead to m- and p-cresols through a procedure analogous to that used for the cumene-to-phenol process. 

---