ARCO process

The addition of an oxygen atom to an olefin to generate an epoxide is often catalyzed by soluble molybdenum complexes. The use of alkyl hydroperoxides such as tert-huty hydroperoxide leads to the efficient production of propylene oxide (qv) from propylene in the so-called Oxirane (Halcon or ARCO) process (79). 

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). 

The reactor combinations for the two reactors in series consist of two fixed-beds for the Arco process an expanded bed followed by a catalytic distillation reactor for lEP a fixed-bed followed by a catalytic distillation reactor for CDTECH and two fixed-beds for Phillips. The Huls process uses an adiabatic reactor for the second reactor. 

Architectural coatings, 18 55-56 economic aspects of, 18 73-74 Architectural fabrics, 13 394 Architectural paints, 18 72 Archives, preservation of, 11 414 Arch Raschig process flow sheet, 13 578 Arc melting techniques, 25 522-523 ARCO process, 23 342 Arc-resistance furnace, 12 304 Arc resistance testing, 19 587 Arctic polar stratospheric clouds, effect on ozone depletion, 17 789-790 Arc vaporization, 24 738 Arc welding, copper wrought alloys,... 

The reaction in Fig. 4.19 is catalyzed by compounds of high-valent, early transition metals such as Mo(VI), W(VI), V(V) and Ti(IV). Molybdenum compounds are particularly effective homogeneous catalysts and are used in the ARCO process in combination with TBHP or EBHP. In the Shell process, on the other hand, a heterogeneous Ti(IV)/Si02 catalyst is used with EBHP in a continuous,... 

The mechanism of the asymmetric epoxidation of allylic alcohols with the Sharpless-Katsuki catalyst is assumed to be very similar to the one described for the Halcon-ARCO process in Section 2.5. The key point is that the chiral tartrate creates an asymmetric environment about the titanium center (Figure 18). When the allylic alcohol and the t-butyl hydroperoxide bind through displacement of alkoxy groups from the metal, they are disposed in such a way as to direct oxygen transfer to a specific face of the C=C double bond. This point is crucial to maximize enantioselectivity. 

This washing treatment is the original feature of the ARCO process. It allows better control of product purity (99 to 99.8 per cent) and, above all, helps to cut capital investment and operating costs by reducing the recirculation inventory stock by two thirds. 

Table 4.17 lists the economic characteristics of the Tatoray and ARCO processes. 

Two examples will indicate improvements that have come about by simple economics of the marketplace. Olefins higher than ethylene are usually converted to the epoxides indirectly by adding hypochlorous acid, then base to split out hydrogen choride (1.24). However, an Arco process does this without formation of by-product salt.230 Dow is switching to the new route.231... 

Thirdly, separation of catalyst and products can be conveniently achieved by extraction with water if the products are water-soluble, e.g., in the hydroformylation of ally] alcohol [10, 11]. In the ARCO process the hydroformylation products are extracted (more than 99%) from the organic reaction medium containing the con-... 

The autoxidation of alkylbenzenes constitutes the industrial route for the production of the corresponding hydroperoxides. The two well-known examples are the production of 1-phenylethyl hydroperoxide in the Shell and ARCO processes for the co-production of styrene and propene oxide, and the production of cumene hydroperoxide for the production of phenol via the Hock process (1,2) A disadvantage of the Hock-process is the co-production of acetone. One possible alternative involves the use of cyclohexylbenzene (CHB) in Scheme 1. 

The ARCO process uses a homogeneous catalyst dissolved in the TEA/ TBHP mixture. Shell uses a heterogeneous catalyst [111. 

Assistance will be provided in making decisions, but will be very specific with references in the open patent literature. It should be apparent in this problem statement of this most timely process study that I must be careful not to release proprietary information which is contained in a very recent patent application for which I am one of the inventors. The results of this comparison of the Texaco process, as devised by your group, with the ARCO process is typical of an exercise that all companies must undertake to analyze the economic viability of all new ventures. 

Other crystallization methods for producing p-xylene include the Maruzen process, which uses ethylene as a direct coolant, the Arco process, which is very similar to the Amoco process, and the three-stage Kmpp-Koppers process. 

Figure 31. ARCO process scheme for the production of high-octane gasoline from natural gas by oxidative coupling of methane and subsequent olefin oligomerization [60].

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