Aromatics from naphtha

Silica-Gel Adsorption. The Arosorb process is an aromatic adsorption process developed by the Sun Oil Co. and uses silica gel to separate aromatics from naphtha reformates (54). Operating and investment costs for Arosorption were presented as follows ... 

In the furnace process, which today dominates carbon black production, oils rich in aromatics from naphtha or gas oil pyrolysis, cat-cracker residues (decant oils) together with mixtures of aromatics from coal tar, are used as feedstock. Table 13.5 summarizes the characteristic data for decant oil, pyrolysis oil from naphtha cracking and a carbon black feedstock derived from coal tar. 

Ali, S. H. Lababidi, H. M. S. Merchant, S. Q. Fahim, M. A. (2003). Extraction of aromatics from naphtha reformates using propylene carbonate. Fluid Phase Equilib. 214, 25-38, ISSN 0378-3812. 

Benzene, toluene, and xylene are made mosdy from catalytic reforming of naphthas with units similar to those already discussed. As a gross mixture, these aromatics are the backbone of gasoline blending for high octane numbers. However, there are many chemicals derived from these same aromatics thus many aromatic petrochemicals have their beginning by selective extraction from naphtha or gas—oil reformate. Benzene and cyclohexane are responsible for products such as nylon and polyester fibers, polystyrene, epoxy resins (qv), phenolic resins (qv), and polyurethanes (see Fibers Styrene plastics Urethane POLYiffiRs). 

M-iscellaneousFxtractions. Additional extractive separations using sulfolane involve (/) mercaptans and sulfides from sour petroleum (45) (2) /-butylstyrene from /-butylethjlbenzene (46) (J) mixtures of close boiling chlorosHanes (47) and (4) aromatics from kerosene (48—50), naphtha (49,51—53), and aviation turbine fuel (54). 

The primary sources of toluene and xylenes are reformates from catalytic reforming units, gasoline from catcracking, and pyrolysis gasoline from steam reforming of naphtha and gas oils. As mentioned earlier, solvent extraction is used to separate these aromatics from the reformate mixture. 

Raffinate. In extraction processes, the stream that has had the extracted material removed from it is called raffinate, in contrast to the other produced stream, the extract. Usually associated with aromatics extraction from naphtha streams. 

This chapter reviews the adsorptive separations of various classes of non-aromatic hydrocarbons. It covers three different normal paraffin molecular weight separations from feedstocks that range from naphtha to kerosene, the separation of mono-methyl paraffins from kerosene and the separation of mono-olefins both from a mixed C4 stream and from a kerosene stream. In addition, we also review the separation of olefins from a C10-16 stream and review simple carbohydrate separations and various acid separations. 

In the middle thirties the reactions of naphtha and certain compounds known to be present in naphtha were being studied in university and industrial laboratories. One of the problems was to find a catalyst that was capable of synthesizing an aromatic from a paraffin. It was reasoned that the hydrogenation-dehydrogenation oxide-type catalysts such as molybdenum oxide and chromium might possess suitable activity at temperatures well below those employed in thermal reforming. 

Extractive distillation was the basis of a process introduced commercially by the Shell Development Co. and put into operation in 1940 at the Houston refinery of the Shell Oil Co., Inc., for separating toluene from virgin stocks (6) subsequently it was used also on hydroformates and cracked naphthas. This process, shown diagrammatically in Figure 3, involves the production of a toluene concentrate by distillation to remove low and high boiling contaminants, which then is extractively distilled with phenol to separate the aromatics from the paraffin (5). The extract is obtained as a bottoms stream from the extractive distillation tower, and is further fractionated in a distillation tower to separate raw toluene from the phenol, after which the toluene is acid treated and redis-... 

Mixtures of gaseous or liquid hydrocarbons which can be vaporized represent the raw materials preferable for the industrial production of carbon black. Since aliphatic hydrocarbons give lower yields than aromatic hydrocarbons, the latter are primarily used. The best yields are given by unsubstituted polynuclear compounds with 3-4 rings. Certain fractions of coal tar oils and petrochemical oils from petroleum refinement or the production of ethylene from naphtha (aromatic concentrates and pyrolysis oils) are materials rich in these compounds. These aromatic oils, which are mixtures of a variety of substances, are the most important feedstocks today. Oil on a petrochemical basis is predominant. A typical petrochemical oil consists of 10-15% monocyclic, 50-60% bicyclic, 25-35% tricyclic, and 5-10% tetracyclic aroma tes. 

Figure 7. Effect of aromatics by-product price structure and naphtha feed price on U.S. ethylene production costs (1000 MM Ibs/yr ethylene production from naphtha feed premium value by-products)...

Figure 7 shows the effect on ethylene production cost from naphtha cracking with BTX aromatics value increases as a parameter. (The basis we have used for determining the effect of aromatics price increases is given in Table XII). Figure 7 indicates that a 5 /gal increase in BTX... 

Edeleanu process a process for refining oils at low temperature with liquid sulfur dioxide (S02), or with liquid sulfur dioxide and benzene applicable to the recovery of aromatic concentrates from naphthas and heavier petroleum distillates. 

Naphtha is divided into two main types, aliphatic and aromatic. Aliphatic naphtha is composed of paraffinic hydrocarbons and cycloparaffins (naphthenes), and may be obtained directly from crude petroleum by distillation. Aromatic naphtha contains aromatics, usually alkyl-substituted benzene, and is very rarely, if at all, obtained from petroleum as straight-run materials often reforming is necessary (Fig. 2). 

Several methods, involving solvent extraction or destructive hydrogenation, can accomplish the removal of aromatic hydrocarbons from naphtha. By destructive hydrodegation methods, aromatic hydrocarbon rings are first ruptured and then saturated with hydrogen, which converts aromatic hydrocarbons into the odorless, straight-chain paraffinic hydrocarbons required in aliphatic solvents. 

Application The Sulfolane process recovers high-purity C6-C9 aromatics from hydrocarbon mixtures, such as reformed petroleum naphtha (reformate), pyrolysis gasoline (pygas), or coke oven light oil (COLO), by extractive distillation with or without liquid-liquid extraction. 

Application To produce high yields of benzene, toluene, xylenes and hydrogen from naphthas via the CCR Aromizing process coupled with RegenC continuous catalyst regeneration technology. Benzene and toluene cuts are fed directly to an aromatics extraction unit. The xylenes fraction, obtained by fractionation and subsequent treatment by the Arofining process for diolefins and olefins removal, is ideal for para-xylene and orthoxylene production. 

Description Aromatics are produced from naphtha in the Aromizing section (1), and separated by conventional distillation. The xylene fraction is sent to the Eluxyl unit (2), which produces 99.9% paraxylene via simulated countercurrent adsorption. The PX-depleted raffinate is isomerized back to equilibrium in the isomerization section (3) with either EB dealkylation-type (XyMax) processes or EB isomerization-type (Oparis) catalysts. High-purity benzene and toluene are separated from non-aromatic compounds with extractive distillation (Morphylane ) processes (4). Toluene and C9 to Cn aromatics are converted to more valued benzene and mixed xylenes in the TransPlus process (5), leading to incremental paraxylene production. 

The distribution of compounds produced by this operation is quite different from that obtained from naphtha. The main reason for this is the pronounced aromaticity" of gas oils, which affects the maximum ethylene yield. Moreover, this parameter may substantially from one gas oil to another, and in comparable ojserating conditions this partly explains the wide differences observed in the distribution of the hydrocarbons formed. The Stone and Webster Company established a correlation between the BMCI (Bureau of Mines Correlation Index) for gas oils and the maximum ethylene yield. The BMCL created in 1940, represents an aromaticity index" deOned by the foDowing equation ... 

China Taiwan has a nameplate ethylene capacity of 3.6 million tonnes a year of ethylene. This makes Taiwan the fourth largest producer of olefins in the Far East. All of the production is from naphtha so that large volumes of propylene, higher olefins and aromatics are also produced. These feedstocks are used to produce a range of polymers, fibre intermediates and petrochemicals in large integrated complexes. 

Naphtha is likely to remain the main feedstock for petrochemical operations because of the abihty of the feedstock to not only dehver both ethylene and propylene, but also BTX aromatics from the rapidly growing fires and speciality polymers markets (nylons, polyester etc.). 

A process involving catalytic dehydrogenation in the presence of hydrogen is known as hydroforming. Toluene, benzene, and other aromatic materials can be economically produced from naphtha feed stocks in this way. After the toluene is separated from the other components, it is condensed and cooled in a process such as the one shown in Fig. P4.87. For every 100 kg of stock charged into the system, 27.5 kg of a toluene and water mixture (9.1% water) are produced as overhead vapor and condensed by the charge stream. Calculate ... 

Toluene. The sources of toluene lie primarily in the catalytic reforming of selected petroleum fractions rich in naphthenes or in the recovery of toluene contained in aromatic concentrate (pyrolysis gasoline) produced as a byproduct of ethylene manufacture—mostly from naphtha/gas oil cracking. U.S. production and pricing for benzene and the aromatics discussed in Sections... 

---