Meta-4 process

Application To produce polymer-grade propylene plus either an isobutylene-rich stream or MTBE by upgrading low-value pyrolysis C4 cuts or butene-rich streams via selective hydrogen and Meta-4 processes. This process is particularly profitable when butadiene markets are weak and propylene demand is strong. 

The CCR Meta-4 process features are a hard, highly active and robust catalyst, low catalyst inventory, low operating temperature and pressure, outstanding yields, liquid-phase operation, and continuous operation and catalyst regeneration. 

Economics ISBL 2004 investment for a Gulf Coast location of a Meta-4 process producing 180,000 tpy propylene is US 19 million. Typical operating cost is 18 per metric ton of propylene. 

Reference Chodorge, J. A., J. Cosyns, D. Commereuc, Q. Debuiss-chert, and P. Travers, Maximizing propylene and the Meta-4 process, Oil Gas 2000. 

Fig. 17.2 The IFP Meta-4 Process for the production of propene from ethene and but-2-ene (adapted from the IFP brochure).

Excellent regioselectivity and stereoselectivity has been achieved in each photocycloaddition mode [45 48], Regiochemistry and stereochemistry in the meta process is decided by the orientation of the addends in the exciplex and by stabilization of biradical intermediates having a change transfer (CT) character (6) by the substituents on the arene. Intermolecular meta cycloaddition of arenes with cycloalkenes proceeds with endo selectivity (7) (Scheme 5). In the ortho-process, selectivities can be controlled mainly by the substituents on the reactants. 

Placed in a completely different and far more fixedly structured domain, the results of the DWQ project were not directly transferable to the CRC 476 IMPROVE. For the support of creative design processes, different approaches were - and are - necessary. Yet the approach of applying methods of meta modeling in domain and application models was expected to succeed there as well. Especially the use of ConceptBase, as described before, was used to achieve a sound conceptual and ontological basis for the modeling aspects, the process extensions to Data Warehousing as researched in the subproject Cl, and the meta process and product repository of the subproject B1. 

Karmiloff-Smith, A., 1986, From meta-processes to conscious access Evidence from chidren s metalinguistic and repair data. Cognition, 23,95-147. 

A brief account of aromatic substitution may be usefully given here as it will assist the student in predicting the orientation of disubstituted benzene derivatives produced in the different substitution reactions. For the nitration of nitrobenzene the substance must be heated with a mixture of fuming nitric acid and concentrated sulphuric acid the product is largely ni-dinitrobenzene (about 90 per cent.), accompanied by a little o-dinitrobenzene (about 5 per cent.) which is eliminated in the recrystallisation process. On the other hand phenol can be easily nitrated with dilute nitric acid to yield a mixture of ortho and para nitrophenols. It may be said, therefore, that orientation is meta with the... 

Synthetic phenol capacity in the United States was reported to be ca 1.6 x 10 t/yr in 1989 (206), almost completely based on the cumene process (see Cumene Phenol). Some synthetic phenol [108-95-2] is made from toluene by a process developed by The Dow Chemical Company (2,299—301). Toluene [108-88-3] is oxidized to benzoic acid in a conventional LPO process. Liquid-phase oxidative decarboxylation with a copper-containing catalyst gives phenol in high yield (2,299—304). The phenoHc hydroxyl group is located ortho to the position previously occupied by the carboxyl group of benzoic acid (2,299,301,305). This provides a means to produce meta-substituted phenols otherwise difficult to make (2,306). VPOs for the oxidative decarboxylation of benzoic acid have also been reported (2,307—309). Although the mechanism appears to be similar to the LPO scheme (309), the VPO reaction is reported not to work for toluic acids (310). 

Other Meta.Is, Although most cobalt is refined by chemical methods, some is electrorefined. Lead and tin are fire refined, but a better removal of impurities is achieved by electrorefining. Very high purity lead is produced by an electrochemical process using a fluosiUcate electrolyte. A sulfate bath is used for purifying tin. Silver is produced mainly by electrorefining in a nitrate electrolyte, and gold is refined by chemical methods or by electrolysis in a chloride bath. 

Ethyltoluene is manufactured by aluminum chloride-cataly2ed alkylation similar to that used for ethylbenzene production. All three isomers are formed. A typical analysis of the reactor effluent is shown in Table 9. After the unconverted toluene and light by-products are removed, the mixture of ethyltoluene isomers and polyethyltoluenes is fractionated to recover the meta and para isomers (bp 161.3 and 162.0°C, respectively) as the overhead product, which typically contains 0.2% or less ortho isomer (bp 165.1°C). This isomer separation is difficult but essential because (9-ethyltoluene undergoes ring closure to form indan and indene in the subsequent dehydrogenation process. These compounds are even more difficult to remove from vinyltoluene, and their presence in the monomer results in inferior polymers. The o-ethyltoluene and polyethyltoluenes are recovered and recycled to the reactor for isomerization and transalkylation to produce more ethyltoluenes. Fina uses a zeoHte-catalyzed vapor-phase alkylation process to produce ethyltoluenes. 

Mass transport selectivity is Ulustrated by a process for disproportionation of toluene catalyzed by HZSM-5 (86). The desired product is -xylene the other isomers are less valuable. The ortho and meta isomers are bulkier than the para isomer and diffuse less readily in the zeoHte pores. This transport restriction favors their conversion to the desired product in the catalyst pores the desired para isomer is formed in excess of the equUibrium concentration. Xylene isomerization is another reaction catalyzed by HZSM-5, and the catalyst is preferred because of restricted transition state selectivity (86). An undesired side reaction, the xylene disproportionation to give toluene and trimethylbenzenes, is suppressed because it is bimolecular and the bulky transition state caimot readily form. 

G. M. Ritcey and A. W. Ashbrook, So/ventExtraction Princip/es andApp/ications to Process Meta//urg, Elsevier Publishing Co., Amsterdam, 1979, Part II, p. 669. 

Precious Meta.1 Ca.ta.lysts, Precious metals are deposited throughout the TWC-activated coating layer. Rhodium plays an important role ia the reduction of NO, and is combiaed with platinum and/or palladium for the oxidation of HC and CO. Only a small amount of these expensive materials is used (31) (see Platinum-GROUP metals). The metals are dispersed on the high surface area particles as precious metal solutions, and then reduced to small metal crystals by various techniques. Catalytic reactions occur on the precious metal surfaces. Whereas metal within the crystal caimot directly participate ia the catalytic process, it can play a role when surface metal oxides are influenced through strong metal to support reactions (SMSI) (32,33). Some exhaust gas reactions, for instance the oxidation of alkanes, require larger Pt crystals than other reactions, such as the oxidation of CO (34). 

The largest known fluonne stenc effect is the rate ratio of lo" at 25 °C for the meta ring fhp m 20 [166 Other dynamic processes that reveal bona fide fluonne stenc effects are the bamers to i-C3H.j group rotation in 21 =69... 

Rubber blends with cure rate mismatch is a burning issue for elastomer sandwich products. For example, in a conveyor belt composite structure there is always a combination of two to three special purpose rubbers and, depending on the rubber composition, the curatives are different. Hence, those composite rubber formulations need special processing and formulation to avoid a gross dissimilarity in their cure rate. Recent research in this area indicated that the modification of one or more rubbers with the same cure sites would be a possible solution. Thus, chlorosulfonated polyethylene (CSP) rubber was modified in laboratory scale with 10 wt% of 93% active meta-phenylene bismaleimide (BMI) and 0.5 wt% of dimethyl-di-(/ r/-butyl-peroxy) hexane (catalyst). Mixing was carried out in an oil heated Banbury-type mixer at 150-160°C. The addition of a catalyst was very critical. After 2 min high-shear dispersive melt mix-... 

Process for Forming Sintered Meta Coalings, Texas Instruments Inc., UK Pat. 1 163 766 (10.9.69)... 

SOMe the enhancement in the meta-position is almost as large as in the para-position. The authors go on to show the applicability of op (g) values to certain solution processes, particularly those in non-aqueous solvents, but including the dissociation of thiophenols in 48% ethanol, the results of Bordwell and Andersen80 to which reference has been made earlier (Section III.A.1). A separation of field/inductive and resonance effects is also essayed for the gas-phase acidities of the phenols, and SOMe and S02Me feature in the discussion. There is reference to a oR° value of + 0.07 for SOMe as an unpublished result of Adcock, Bromilow and Taft (cf. 0.00 from Ehrenson and coworkers65 and — 0.07 from Katritzky, Topsom and colleagues128.)... 

It is well known that certain microorganisms are able to effect the deracemization of racemic secondary alcohols with a high yield of enantiomerically enriched compounds. These deracemization processes often involve two different alcohol dehydrogenases with complementary enantiospedficity. In this context Porto ef al. [24] have shown that various fungi, induding Aspergillus terreus CCT 3320 and A. terreus CCT 4083, are able to deracemize ortho- and meta-fluorophenyl-l-ethanol in good... 

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