Oxidation butane

Figure A3.14.14. A cellular flame in butane oxidation on a burner. (Courtesy of A C McIntosh.)...

World installed capacity for formic acid is around 330,000 t/yr. Around 60% of the production is based on methyl formate. Of the remainder, about 60% comes from Hquid-phase oxidation and 40% from formate salt-based processes. The largest single producer is BASF, which operates a 100,000 t/yr plant at Ludwigshafen in Germany. The only significant U.S. producer of formic acid is Hoechst-Celanese, which operates a butane oxidation process. 

The use of an organic medium yields an increase in the surface area of the VOHPO O.5H2O (70,126). This increase in surface area is carried over to the resulting vanadyl pyrophosphate phase (123) and is desirable because a concurrent increase in activity toward butane oxidation is observed (70). 

Butane-Based Fixed-Bed Process Technology. Maleic anhydride is produced by reaction of butane with oxygen using the vanadium phosphoms oxide heterogeneous catalyst discussed earlier. The butane oxidation reaction to produce maleic anhydride is very exothermic. The main reaction by-products are carbon monoxide and carbon dioxide. Stoichiometries and heats of reaction for the three principal reactions are as follows ... 

This process may be competitive with butane oxidation (see Hydrocarbon oxidation) which produces a spectmm of products (138), but neither process is competitive with the process from synthesis gas practiced by Monsanto (139) and BASF (140) which have been used in 90% of the new acetic acid capacity added since 1975. 

Like propane, n-hutane is mainly obtained from natural gas liquids. It is also a hy-product from different refinery operations. Currently, the major use of n-hutane is to control the vapor pressure of product gasoline. Due to new regulations restricting the vapor pressure of gasolines, this use is expected to he substantially reduced. Surplus n-butane could be isomerized to isobutane, which is currently in high demand for producing isobutene. Isobutene is a precursor for methyl and ethyl tertiary butyl ethers, which are important octane number boosters. Another alternative outlet for surplus n-butane is its oxidation to maleic anhydride. Almost all new maleic anhydride processes are based on butane oxidation. 

For many years the catalytic air oxidation of benzene was the main source of maleic anhydride. Obviously, two carbons from each ring are wasted as carbon dioxide in this process. Although some is still made that way, most modem maleic anhydride plants are based on butane oxidation. Because butane is forecast to be plentiful and low-cost, new routes to four-carbon chemicals from maleic anhydride are under active development. 

Johnson EL, MR Hyman (2006) Propane and -butane oxidation by Pseudomonasputida Gpol. Appl Environ Microbiol 72 950-952. 

The reactivity of vanadyl pyrophosphate (VO)2P207, catalyst for n-butane oxidation to maleic anhydride, was investigated under steady and unsteady conditions, in order to obtain iirformation on the status of the active surface in reaction conditions. Specific treatments of hydrolysis and oxidation were applied in order to modify the characteristics of the surface layer of the catalyst, and then the unsteady catalytic performance was followed along with the reaction time, until the steady original behavior was restored. It was found that the transformations occurring on the vanadyl pyrophosphate surface depend on the catalyst characteristics (i.e., on the PfV atomic ratio) and on the reaction conditions. 

The industrial catalyst for n-butane oxidation to maleic anhydride (MA) is a vanadium/phosphoras mixed oxide, in which bulk vanadyl pyrophosphate (VPP) (VO)2P207 is the main component. The nature of the active surface in VPP has been studied by several authors, often with the use of in situ techniques (1-3). While in all cases bulk VPP is assumed to constitute the core of the active phase, the different hypotheses concern the nature of the first atomic layers that are in direct contact with the gas phase. Either the development of surface amorphous layers, which play a direct role in the reaction, is invoked (4), or the participation of specific planes contributing to the reaction pattern is assumed (2,5), the redox process occurring reversibly between VPP and VOPO4. 

Self-assembled nanorods of vanadium oxide bundles were synthesized by treating bulk V2O5 with high intensity ultrasound [34]. By prolonging the duration of ultrasound irradiation, uniform, well defined shapes and surface structures and smaller size of nanorod vanadium oxide bundles were obtained. Three steps which occur in sequence have been proposed for the self-assembly of nanorods into bundles (1) Formation of V2O5 nuclei due to the ultrasound induced dissolution and a further oriented attachment causes the formation of nanorods (2) Side-by-side attachment of individual nanorods to assemble into nanorods (3) Instability of the self-assembled V2O5 nanorod bundles lead to the formation of V2O5 primary nanoparticles. It is also believed that such nanorods are more active for n-butane oxidation. 

VIII.B.2. Atomic-Resolution ETEM of Butane Oxidation. 203... 

The selective oxidation of ra-butane to give maleic anhydride (MA) catalyzed by vanadium phosphorus oxides is an important commercial process (99). MA is subsequently used in catalytic processes to make tetrahydrofurans and agricultural chemicals. The active phase in the selective butane oxidation catalyst is identified as vanadyl pyrophosphate, (V0)2P207, referred to as VPO. The three-dimensional structure of orthorhombic VPO, consisting of vanadyl octahedra and phosphate tetrahedra, is shown in Fig. 17, with a= 1.6594 nm, b = 0.776 nm, and c = 0.958 nm (100), with (010) as the active plane (99). Conventional crystallographic notations of round brackets (), and triangular point brackets (), are used to denote a crystal plane and crystallographic directions in the VPO structure, respectively. The latter refers to symmetrically equivalent directions present in a crystal. 

Fig. 20. (a) Active sites observed by in situ atomic-resolution ETEM structural modification of VPO in n-butane along (201) indicates the presence of in-plane anion vacancies (active sites in the butane oxidation) between vanadyl octahedra and phosphate tetrahedra. (b) Projection of (010) VPO (top) and generation of anion vacancies along (201) in n-butane. V and P are denoted. Bottom model of novel glide shear mechanism for butane oxidation catalysis the atom arrowed (e.g., front layer) moves to the vacant site leading to the structure shown at the bottom. 

Gao, X. Banares, M.A. Wachs, EE. Ethane and w-butane oxidation over supported vanadium oxide catalysts An in situ UV-visible diffuse reflectance spectroscopic investigation. J. Catal. 1999,188, 325-331. 

Other methods for the preparation of acetic acid are partial oxidation of butane, oxidation of ethanal -obtained from Wacker oxidation of ethene-, biooxidation of ethanol for food applications, and we may add the same carbonylation reaction carried out with a cobalt catalyst or an iridium catalyst. The rhodium and iridium catalysts have several distinct advantages over the cobalt catalyst they are much fester and fer more selective. In process terms the higher rate is translated into much lower pressures (the cobalt catalyst is operated by BASF at pressures of 700 bar). For years now the Monsanto process (now owned by BP) has been the most attractive route for the preparation of acetic acid, but in recent years the iridium-based CATTVA process, developed by BP, has come on stream. 

Butane oxidation Cobalt acetate 300-450 800 57 Acetaldehyde + acetone + methanol... 

Acetic acid, CH3COOH, can be made by the oxidation of acetaldehyde, CH3CHO by catalytic addition of CO to methanol or by butane oxidation. Most acetic acid is used to make vinyl acetate or cellulose acetate, which are the intermediates for plastics, paints, adhesives, yarn, and cigarette filters. 

In Asia, Asahl and Mitsubishi have commercialized a process using isobutylene or tertiary butyl alcohol to malce methacrolein. Then they further oxidize it to methacryiic acid, MAA, which is then esterified with methanol to MMA. The same process might eventually start with iso butane oxidation to bypass the olefin step. 

Synonyms Agrisynth THF AI3-07570 Biethylene oxide BRN 0102391 a,5-Butane oxide alpha, c/e7ta-Butane oxide Butylene oxide CCRIS 6276 Cyclotetramethylene oxide Diethylene oxide Dynasolve 150 EINECS 203-726-8 1,4-Epoxybutane Furanidine Hydrofuran NCI-C60560 NSC 57858 Oxacyclopentane Oxolane RCRA waste number U213 Tetramethylene oxide TFIF UN 2056. 

The solids analysis described above can be taken to yet another level by correlating the color measurement to chemical properties. An excellent model system is vanadium pyrophosphate (VPO), which is a well-known catalyst for butane oxidation to maleic anhydride. During the synthesis of the catalyst precursor, solid V2O5 particles are dispersed in a mixture of benzyl alcohol and i-butanol. In this slurry phase, the vanadium is partly reduced. Addition of phosphoric acid leads to a further reduction and the formation of the VPO structure. With a diffuse reflectance (DR) UV-vis probe by Fiberguide Ind., the surface of the suspended solid particles could be monitored during this slurry reaction. Four points can be noted from Figure 4.4 ... 

The (VO)2P20t produced maleic anhydride with 60%-selectivity in the butane oxidation at 713 K. When Si02 was deposited on the surface of (VO)2P20 (the atomic ratio of Si to V at the surface was 6) by the reaction of Si(CH3>4 + O2 at 773 K, the surface lost the catalytic activity. TEM-EDX observation revealed that Si02... 

The active site of (VO)2P20 for the butane oxidation is thought to be V +(=0)-0-V4+, which is located on the (100) face of (VO)2P20 (- )> where XRD lines were indexed following Gorbunova and Linde (14),... 

Figure 5. W/F dependencies of the conversion for the butane oxidation over (VO)2P20 - (O) (VO)2P207 ( ) Si02/(V0>2P207 fractured once.

Figure 6. Time courses of butane oxidation over (VO)2P207 and (SO)<2 2 1 fractured at 713 K. (O) parent, ( ) fractured once,...

In conclusion, the crystal faces of (VO)2P207 different reactivities for butane oxidation the (100) face was selective for the formation MA and the side faces such as (001) are active for non-selective oxidation as illustrated in Figure 7. 

---