Basic Chemicals from Aromatic Hydrocarbons

Today, distillation is a key to production of most commodity chemicals. It is used to make gasoline from crude oil. It is basic to the four most important separations of organics aliphatic from aromatic hydrocarbons, linear from branched hydrocarbons, olefins from alkanes, and alcohols from water. One essay on choosing separation processes starts with the question Why not distillation After then discussing over fifty other processes, it repeats, Are you sure you do not want to use distillation ... 

Aromatic compounds (also called arenes) include benzene and compounds that resemble benzene in chemical behavior. Those properties of benzene that distinguish it from aliphatic hydrocarbons are called aromatic properties. Usually the structures of aromatic compounds are formed with benzene as the basic building block, although a few... 

Niederer [100] used ion trap mass spectrometry and negative ion chemical ionisation to determine nitro- and oxypolyaromatic hydrocarbons in soils. Meyer et al. [101] have described a simple and reproducible method which provides the simultaneous determination of polycyclic aromatic hydrocarbons and het-eropolycyclic aromatic hydrocarbons (N, S, O) and their metabolites in contaminated soils. Contaminants extracted from the soil sample were separated by polarity and acid-base characteristics using solid-phase extraction on silica gel and a strong basic anion exchange material. A subfraction containing PANHs and neutral metabolites was subsequently fractionated into neutral and basic... 

The present world rcscr es of natural gas that contains mainly methane are still underutilized due to high cost of transportation. Considerable interest is therefore presently shown in the conversion of methane to transportable liquids and feedstocks in addition to its previous sole use for heating purposes by combustion. One possible new route for the utilization of methane derived from natural gas or other sources for conversion to more valuable higher hydrocarbons is the methylation of aromatic hydrocarbons. This chapter provides a general overview of the work that has been done so far on the use of methane for catalytic methylation of model aromatic compounds and for direct liquefaction of coal for the production of liquid hydrocarbons. The review is especially focused on the use of both acidic and basic zeolites in acid-catalyzed and base-catalyzed methylation reactions, respectively. The base-catalyzed methylation reaction covered in this discussion is mainly the oxidative methylation of toluene to produce ethylbenzene and styrene. This reaction has been found to occur over basic sites incorporated into zeolites by chemical modification or by changing the electronegative charge of the zeolite framework. 

The tenii petrochemicals refers to the basic chemicals that are derived from refinery petroleum cuts. They are produced by separation of the byproducts from the cracking (pyrolysis) of hydrocarbon streams. These streams range from natural gas to the heavy distillate (gas oil) cuts from a refinery primary fractionator. Some chemicals, such as the aromatics, are separated from various refinery streams. Figure 13.43 is simplified schematic of a petrochemical process. 

A basic chemical hydrocarbon based on a single or multiple benzene rings (C6H6). Some of the more common aromatics include benzene, toluene, xylene, and phenol. They exhibit a somewhat sweet, yet sickly odor. The term aromatic was assigned before the physical mechanism determining aromaticity was discovered, and was derived from the fact that many of the compounds have a sweet scent. They will burn with a sooty yellow flame because of the high carbon-hydrogen ratio. 

There are two basic types of chemical structures, styrene and acryhc. The styrene-based materials described above are aromatic hydrocarbons. Acrylic resins are straight-chained hydrocarbons based on polyacrylate and polymethaciylate. DVB is still used as a cross-linker in these resins, but the acrylics differ from the styrenics in that the active exchange site is part of the physical structure. This means that their physical and chemical stabilities are intertwined. When an acrylic resin chemically degrades, it is usually at the exchange site, which is the weak link. This destroys the physical structure. As an aciyhc resin... 

---