Shell processes

Shell Chlorine Process. The Shell process produces CI2 from the HCl usiag air or O2 ia the preseace of cupric and other chlorides on a siUcate carrier (71). The reaction proceeds at an optimal rate ia the temperature range of 430—475°C at an efficiency of 60—70%. A manufactuting unit was built by Shell ia the Netherlands (41,000 t/yr) and another ia ladia (27,000 t/yr). Both plants have been closed down. 

Shell process. Universal Oil Pro-ducts sulfolane sulfolane selectivity and capacity insensitive to water content caused by steam-stripping during solvent recov-ery heavy paraffinic countersolvent use 120 rotating-disk contactor, up to 4 m in diameter the high selectivity and capacity of sulfolane leads to low solvent-feed ratios, and thus smaller equip-ment... 

As of this writing, the process has not been commercialized, but apparendy the alcohol can be separated from its propylene oxide coproduct process to maintain an economically competitive position. The formation of organic hydroperoxides is a concern, as it was in the Shell process. 

Isopropyl alcohol can be oxidized by reaction of an a,P-unsaturated aldehyde or ketone at high temperature over metal oxide catalysts (28). In one Shell process for the manufacture of aHyl alcohol, a vapor mixture of isopropyl alcohol and acrolein, which contains two to three moles of alcohol per mole of aldehyde, is passed over a bed of uncalcined magnesium oxide [1309-48-4] and zinc oxide [1314-13-2] at 400°C. The process yields about 77% aHyl alcohol based on acrolein. 

It is carried out in the Hquid phase at 100—130°C and catalyzed by a soluble molybdenum naphthenate catalyst, also in a series of reactors with interreactor coolers. The dehydration of a-phenylethanol to styrene takes place over an acidic catalyst at about 225°C. A commercial plant (50,51) was commissioned in Spain in 1973 by Halcon International in a joint venture with Enpetrol based on these reactions, in a process that became known as the Oxirane process, owned by Oxirane Corporation, a joint venture of ARCO and Halcon International. Oxirane Corporation merged into ARCO in 1980 and this process is now generally known as the ARCO process. It is used by ARCO at its Channelview, Texas, plant and in Japan and Korea in joint ventures with local companies. A similar process was developed by Shell (52—55) and commercialized in 1979 at its Moerdijk plant in the Netherlands. The Shell process uses a heterogeneous catalyst of titanium oxide on siHca support in the epoxidation step. Another plant by Shell is under constmction in Singapore (ca 1996). 

Transition metal oxides or their combinations with metal oxides from the lower row 5 a elements were found to be effective catalysts for the oxidation of propene to acrolein. Examples of commercially used catalysts are supported CuO (used in the Shell process) and Bi203/Mo03 (used in the Sohio process). In both processes, the reaction is carried out at temperature and pressure ranges of 300-360°C and 1-2 atmospheres. In the Sohio process, a mixture of propylene, air, and steam is introduced to the reactor. The hot effluent is quenched to cool the product mixture and to remove the gases. Acrylic acid, a by-product from the oxidation reaction, is separated in a stripping tower where the acrolein-acetaldehyde mixture enters as an overhead stream. Acrolein is then separated from acetaldehyde in a solvent extraction tower. Finally, acrolein is distilled and the solvent recycled. 

TABLE 8 Composition of the Ethylene Oligomer Product of the Shell Process ... 

FIG. 5 Hydroformylation of higher molecular weight olefins with a ligand-modified cobalt carbonyl catalyst [HCo(CO)3PR3] (Shell process). 

Should pure olefin be used for alkylation (Shell process), the organic phase consists of benzene, LAB, and heavy alkylate and is fractionally distilled, after which the remaining HF is usually removed by stripping. When using olefin as a solution in paraffin (Pacol and Hiils process) for alkylation, the organic phase contains additional large quantities of paraffin which have to be separated out by distillation and used again in the production of olefin. 

Stephanopoulos, G., Artificial Intelligence What Will Its Contributions Be to Process Control In The Second Shell Process Control Workshop (D. M. Prett, C. E. Garcia, and B. L. Ramaker, eds.), p. 591, Butterworths, Sloneham, MA, 1990. 

Cobalt carbonyls are the oldest catalysts for hydroformylation and they have been used in industry for many years. They are used either as unmodified carbonyls, or modified with alkylphosphines (Shell process). For propene hydroformylation, they have been replaced by rhodium (Union Carbide, Mitsubishi, Ruhrchemie-Rhone Poulenc). For higher alkenes, cobalt is still the catalyst of choice. Internal alkenes can be used as the substrate as cobalt has a propensity for causing isomerization under a pressure of CO and high preference for the formation of linear aldehydes. Recently a new process was introduced for the hydroformylation of ethene oxide using a cobalt catalyst modified with a diphosphine. In the following we will focus on relevant complexes that have been identified and recently reported reactions of interest. 

The Shell process uses partial oxygen gasification. Because insufficient oxygen exists for complete combustion (20-30% of the oxygen required for complete combustion is used), only a fraction of carbon in the coal is oxidized completely to C02. The heat released from this combustion provides most of the energy needed for endothermic coal gasification reactions and raises the gasifier temperature. Some steam is usually added to prevent excessive... 

Figure 5.1. The generations of oxo processes [3] (symbolized by full points).A, First generation Ruhrchemie process 1943 (diaden process [4]) B, second generation Ruhrchemie process C, second generation BASF process D, second generation Kuhlmann process E, third generation Shell process F, third generation LPO (UCC) process G, third generation BASF process H, third generation Exxon (Kuhlmann) process I, fourth generation Ruhrchemie/Rhone-Poulenc process...

Phosphine modified cobalt catalysts the Shell process... 

The linearity of the product of the Shell process is higher, 75-90% versus 60-70% for the non-ligand modified process. The reason for this is not entirely clear on steric grounds one might expect that the linear alkyl and acyl complexes are more stable leading to a higher linearity. Electronically the effects on rate and selectivity cannot be easily rationalised. 

Hoechst-Ruhrchemie (now Celanese) reported that no detectable losses of rhodium occur. We assume that propene is stripped from the aldehyde product and finally distillation of the aldehyde is conducted to separate the branched (8%) and linear product (92%). Note that the amounts of water lost in the aldehyde phase have to be replaced. Note also that by-products arising from aldol condensation, if any, are separated from the catalyst together with the product. These heavy ends end up in the bottom of the product distillation, which is advantageous, as the bottom can be sent to an incinerator. In processes such as the Shell process (Figure 7.6), the heavy end is a mixture of... 

The typical size of a Shell process plant described here is 250-350,000 tons per year. The total production of higher olefins via this and similar routes is estimated to be 2 million tons annually. A large part of the alkenes are produced for captive use, i.e. for use by the producing company itself. 

The Shell process based on a nickel phosphine catalyst... 

In the first process the yield does not exceed 65% of the starting compound due to simultaneous formation of 1,2-propanediol, while, in the second, a yield of 80% is obtained. Adding the fact that the market price of ethylene oxide is lower than acrolein, the Shell process can be regarded as economically more favorable. This is reflected in the much higher production volume reported for the production of 1,3-PD from ethylene oxide, which amounted to 45,000 t/a in 1999 as opposed to 9000 t/a from acrolein. The relatively high production costs with the acrolein process have probably induced the Dupont Company to invest in research efforts to further develop the biological process (see below). 

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