1-butene to butadiene

Feed enters the reactor at tube side, oxygen at shell side. Oxidative dehydrogenation of 1-butene to butadiene. W3Sb203 catalyst placed in the pores of the tube. T 462 C. Conversion 30%, Selectivity 92%. T = 505°C. Conversion 57%, Selectivity 88%. ... 

Froment and BischofT (19) report a study of the dehydrogenation of 1-butene to butadiene on a chromia-alumina catalyst. Neglecting isomerization of 1-butene, the following steps are postulated ... 

The use of a membrane reactor for shifting equilibrium controlled dehydrogenation reactions results in increased conversion, lower reaction temperatures and fewer byproducts. Results will be presented on a palladium membrane reactor system for dehydrogenation of 1-butene to butadiene, with oxidation of permeating hydrogen to water on the permeation side. The heat released by the exothermic oxidation reaction is utilized for the endothermic dehydrogenation reaction. 

Figure 3 Selectivity in product versus D H c-H reactant D°H c-H or C-C product at 30% conversion. 1, Ethylbenzene to Styrene. 2, 1-Butene to Butadiene. 3, Acrolein to Acrylic Acid. 4, Ethane to Ethylene. 5, n-Butane to Maleic Anhydride. 6, Propene to Acrolein. 7, Methanol to Formaldehyde. 8, Ethanol to Acetaldehyde. 9, Propane to Propene. 10, n-Butane to Butenes. 11, Propane to Acrolein. 12, Methane to Ethane. 13, Ethane to Acetaldehyde. 14, Methane to Formaldehyde [1].

Examples include hydrogenation of propanal over nickel, dehydrogenation of ethanol over copper-cobalt, dehydrogenation of methylcyclohexane to toluene over platinum, hydroformylation of olefins catalyzed by cobalt hydrocarbonyls on solid polymers, hydrogen-ion catalyzed hydration of olefins on ion exchangers, dehydrogenation of 1-butene to butadiene over chromia-alumina, and various hypothetical reactions. 

Batist, Lippens, and Schuit [138] have attempted to add more detail to the above mechanism. Their scheme is in part based on observations of the activity of catalysts with a wide range of Bi/Mo ratios for the oxidative dehydrogenation of 1-butene to butadiene. Steps are ... 

The first of these is normal bismuth molybdate, Bi2(Mo04)3. Activities of many compositions in this series were tested for conversion of 1-butene to butadiene by Batist and co-workers 138). Surface areas were of the order of 0.2 m /gm. The most active region was 40-70 at. 

Suppose further that we want to avoid dehydrogenation of 1-butene to butadiene ... 

Although the aim of this chapter is to show how a thermodynamic relationship between A and AI allows to predict the type of catalysts needed for a reaction, it is worth recalling that A can be correlated with experimental parameters related to catalysis, or values of selectivity, provided the same reaction is studied [33]. For example, by using data proposed by Matsuura [60], the heat of adsorption A//ads for a series of catalysts of oxidation of 1-butene to butadiene, or the Mossbauer quadruple shift values for Fe +-containing catalysts of propene ammoxidation, could be related to the A value of the respective catalysts [33]. In a study of the ODH... 

Our results rest, on the one hand, on the study of a model reaction (oxygen aided dehydration of N-ethyl formamide (5,6,14,15,16)) which allowed the identification of catalytic sites created through the remote control (namely Brdnsted acidic sites), and, on the other hand, on the oxidation of isobutene to methacrolein and the oxidative dehydrogenation of 1-butene to butadiene. In these studies, the catalysts have been prepared by mectianically mixing oxides prepared separately (about 40 different mixtures were studied). 

There are currentiy three important processes for the production of isobutylene (/) the extraction process using an acid to separate isobutylene (2) the dehydration of tert-huty alcohol, formed in the Arco s Oxirane process and (3) the cracking of MTBE. The expected demand for MTBE wHl preclude the third route for isobutylene production. Since MTBE is likely to replace tert-huty alcohol as a gasoline additive, the second route could become an important source for isobutylene. Nevertheless, its avaHabHity wHl be limited by the demand for propylene oxide, since it is only a coproduct. An alternative process is emerging that consists of catalyticaHy hydroisomerizing 1-butene to 2-butenes (82). In this process, trace quantities of butadienes are also hydrogenated to yield feedstocks rich in isobutylene which can then be easHy separated from 2-butenes by simple distHlation. 

The conjugated diene (including the trans-trans, trans-cis, and cis-cis isomers) can further add ethylene to form Cg olefins or even higher olefins (/). The mechanism of isomerization is proposed to be analogous to butene isomerization reactions (4, 8), i.e., 1-butene to 2-butene, which involves hydrogen shifts via the metal hydride mechanism. A plot of the rate of formation of 2,4-hexadiene vs. butadiene conversion is shown in Fig. 2. 

Diadsorbed diolefins, 30 33 Diadsorbed species, 30 61, 71 Diagonalized matrix, 32 284—286, 288 ammonia synthesis, 32 294—297 n-butane dehydrogenation, 32 309-313 butenes isomerization, 32 305-308 1-butene to 1,3-butadiene dehydrogenation, 32 297-298... 

Although not a separate process, isomerization plays an important role in pretreatment of the alkene feed in isoalkane-alkene alkylation to improve performance and alkylate quality.269-273 The FCC C4 alkene cut (used in alkylation with isobutane) is usually hydrogenated to transform 1,3-butadiene to butylenes since it causes increased acid consumption. An additional benefit is brought about by concurrent 1-butene to 2-butene hydroisomerization. Since 2-butenes are the ideal feedstock in HF alkylation, an optimum isomerization conversion of 70-80% is recommended.273... 

It is advantageous to pretreat butene feeds before alkylation.294-298 1,3-Butadiene is usually hydrogenated (to butenes or butane) since it causes increased acid consumption. The additional benefit of this process is that under hydrogenation conditions alkene isomerization (hydroisomerization) takes place, too. Isomerization, or the transformation of 1-butene to 2-butenes, is really attractive for HF alkylation since 2-butenes give better alkylate (higher octane number) in HF-cata-lyzed alkylation. Excessive 1,3-butadiene conversion, therefore, ensuring 70-80% isomerization, is carried out for HF alkylation. In contrast, approximately 20% isomerization is required at lower butadiene conversion for alkylation with H2SO4. 

Abd. El-Salaam et al. [1] have studied the catalytic activity of various bismuth molybdates for the oxidative dehydrogenation of 2,5-dihydro-furan to furan. A close correlation with the oxidation of butene to butadiene is expected and was indeed observed. 

The reduction of transition metal oxides and of Sn02 + Sb2Os by 1-butene and butadiene were investigated. A single parameter defined as the heat necessary to dissociate 1/2 02 from the oxide, determined the type of reaction. Starting from Q0 = 17 (MnOz) and proceeding to Q0 = 70 (Sn02), the reduction produces ... 

In (12-17) measurements in fluidized beds of 4 cm, 15 cm and 45 cm diameter are reported. On the laboratory scale i.e. in the 4 cm dia. bed the catalyst screening was carried out using 1-butene and butadiene as a feedstock (12). Scale-up problems including the gas distributor design and the redispersion of gas in the bed by screen plates were studied in two pilot plants with bed diameters of 15 and 45 cm, respectively (12,13,14). The hydrocarbon feed varied in composition from 30 to 35 mole % n-butenes, 30 to 32 mole % butadiene, 29 to 35 mole % i-butene and about 7 mole % butane. 

Figure 2 Selectivity at 30% conversion for the reactions indicated as a function ofD°H C-H(reactant) - D°HC-h or c-c (product). 1 ethylbenzene to styrene 2. 1-butene to 1, 3-butadiene 3. toluene to benzoic acid 4. acrolein to acrylic acid 5. ethane to enthylene 6. n-butane to maleic anhydride 7. benzene to phenol 8. toluene to benzaldehyde 9. propene to acrolein 10. 1-butene to 2-butanone 11. isobutene to isobutene 12. methanol to formaldehyde 13. methacrolein to methacyclin acid 14. propane to propene 15. ethanol to acetaldehyde 16. isobutene to methacrolein 17. n-butane to butene 18. benzene to maleic anhydride 19. propane to acrolein 20. methane to ethane 21. ethane to acetaldehyde, 22. isobutane to methacrylic acid 23. methane to formaldehyde 24. isobutane to methacrolein.

This conversion, similar to that of butenes to butadiene (see Section 6.1.1.1), is carried out by Shell in the presence of steam, on an Fe203/Cr203/K2C03 catalyst, at about 600"C The effluent is cooled by oil which absorbs the polymers formed The gas is then compressed before separation, which comprises extractive distillation with aqueous aceto> nitrile, followed by rectification of the isoprene. Shell daims the ability to treat butenes and isoamylenes simultaneously to produce butadiene and isoprene. Some idea of the composition of the effluents from sulfuric add extraction and dehydrogenation is given by Table 6.6. 

Figure 5 shows in the decomposition of 1-butene that butadiene, methane, and C3 products (C3H4 -f C3H6) are produced in essentially equal amounts at low conversion. A decrease in the CH4 C3H6 ratio parallels the formation of C5 products. As conversion increases, the C5 products decompose to C2 and C3 products, and finally at the higher conversions all products appear to decompose to methane and ethylene. 

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