BP cativa™ process

The carbonylation of methanol was developed by Monsanto in the late 1960s. It is a large-scale operation employing a rhodium/iodide catalyst converting methanol and carbon monoxide into acetic acid. An older method involves the same carbonylation reaction carried out with a cobalt catalyst (see Section 9.3.2.4). For many years the Monsanto process has been the most attractive route for the preparation of acetic acid, but in recent years the iridium-based CATIVA process, developed by BP, has come on stream (see Section 9.3.2) ... 

There has been a recent resurgence of interest in iridium catalysed methanol carbonylation, arising from the commercialisation by BP Chemicals of the Cativa process. This uses a promoted iridium catalyst and has now superseded the rhodium catalyst on a number of plants. Its success relies on the discovery of promoters which increase catalytic activity, particularly at commercially desirable low water concentrations. HP IR spectroscopy has been used to investigate the behavior of... 

In 1986, BP Chemicals became the owners of the Monsanto technology. They subsequently also developed their own Cativa process, aimounced in 1996, carbonylation of MeOH to AcOH catalysed by Ir and Mel and promoted with specific metal iodides [8]. As with the improvements in the original Monsanto Rh process, Cativa had benefits such as improved catalyst stability and more favorable operating conditions [9]. 

The major conventional processes for the production of acetic acid include the carbonylation of methanol (originally developed by Monsanto, and now carried out by several companies, such as Celanese-ACID OPTIMIZATION, BP-CATIVA, etc.), the liquid-phase oxidation of acetaldehyde, still carried out by a few companies, and the liquid-phase oxidation of n-butane and naphtha. More recent developments include the gas-phase oxidation of ethylene, developed by Showa Denko K.K., and the liquid-phase oxidation of butenes, developed by Wacker [2a],... 

This iridium reaction is the basis of BP s new Cativa process launched in 1996,73 which offers significant operational efficiency gains and is expected to eventually replace the current rhodium catalysts. 

Interest in iridium-catalyzed methanol carbonylation was rekindled in the 1990 s when BP Chemicals developed and commercialized the Cativa process, which utilizes an iridium/iodide catalyst and a ruthenium promoter. This process has the important advantage that the highest catalytic rates occur at significantly lower water concentration (ca. 5% wt) than for Monsanto s... 

For approximately 30 years, the most successful industrial process for the carbonylation of methanol relied on an iodide-promoted rhodium catalyst. This technology, originally developed by Monsanto and acquired by BP Chemicals in 1986, is responsible for the majority of the acetic acid synthesized industrially. Since then, the most important development in industrial carbonylation chemistry is the Cativa process, announced by BP Chemicals in 1996. ... 

In 1996 BP announced the commercialization of their version of a low-water methanol carbonylation technology named Cativa based upon a promoted iridium catalyst. The Cativa process replaced the high-water Monsanto process which had been used by BP. 

Since the development of Cativa , BP has converted three world-scale acetic acid plants from the old Rh-based high-water Monsanto technology to the Ir-based low-water process. Significant capital and operating cost savings were achieved from the conversion of a Rh-based process to an Ir-based process. Also, the start-up in 2000 of a 500 X 10 metric ton per year acetic acid plant in Malaysia uses the Cativa process [20d]. 

The latest advance in carbonylation of methanol is the use of an Ir catalyst. Introduced as the Cativa process in 1996 by BP Chemicals, Ir-catalyzed production of acetic acid is now used worldwide.93 The catalytic cycle, called the... 

Resulting from these findings, Cativa , an iridium/iodide-catalyzed process, which utilizes a ruthenium promoter, was commercialized by BP in 1995 [44,120-123]. The Cativa process was initially retrofitted to an... 

Although it is a general perception that third-row transition metals are less active as catalysts than their lighter congeners, the iridium-complex-catalyzed reaction of the Cativa process has been successfully commercialized by BP and operates in a number of plants worldwide. High activity is achieved with the aid of a ruthenium promoter that moderates the iodide concentration, and optimal performance is obtained at relatively low water concentrations. 

Acetic acid Ir/I7Ru Cativa -process, BP Chemicals, 1996... 

Iridium-Catalyzed Carbonylation of Methanol BP s Cativa Process... 

Scorpionate or pyrazole V(V) 1-4, 6, 10, and 15, and Re(in) 11, 12, 16, 17, 24-26 complexes have been used as catalysts for the carboxylation of gaseous alkanes via single-pot conversions [5a,fj. These syntheses of carboxylic acids are much simpler than those used in industry. For instance, in the case of the conversion of methane into acetic acid, the current industrial routes commonly involve three distinct stages and use more expensive catalysts and harder experimental conditions (e.g., the Mosanto and BP-Amoco Cativa processes of carbonylation of methanol, at the third stage, are based on Rh and Ir catalysts, respectively) [8b]. 

Between 1995 and 2000, BP Chemicals commercialized and began to operate the Cativa process for the production of acetic acid. The catalyst is cz5-[Ir(CO)2l2] in the presence of a ruthenium-based promoter (e.g. Ru(CO)4l2) or an iodide promoter (a molecular iodide, e.g. Inl3). Catalyst... 

For a long time it was known that group VIII metal carbonyls are efficient catalysts for carbonylation reactions. In 1996, BP developed a new catalyst system for methanol carbonylation based on iridium (additionally promoted by iodine and Ru-salts), called the Cativa process. Fundamental studies had shown before that the oxidative addition of methyl iodide to iridium is 150-times faster than to rhodium. Thus, in the Cativa process this step is no longer rate determining (as in the case of Rh-based methanol carbonylation). The slowest step in the iridium-cyde is the insertion of CO. This step involves the elimination of iodide and coordination of an additional CO ligand to iridium (Figure 6.15.6). Accordingly, the reaction rate can be described by Eq. (6.15.8) ... 

In the BASF process, methanol and CO are converted in the liquid phase by a homogeneous Co-based catalyst. The reaction takes place in a high-pressure Hastelloy reactor. In recent decades the BASF process has been increasingly replaced by low-pressure alternatives mainly due to lower investment and operating costs. In the low-pressure Monsanto process methanol and CO react continuously in liquid phase in the presence of a Rhl2 catalyst. In 1996, BP developed a new attractive catalyst based on iridium (Cativa process) the oxidative addition of methyl iodide to iridium is 150-times faster than to rhodium. The search for acetic acid production processes with even lower raw material costs has led to attempts to produce acetic acid by ethane oxidation. In the near future ethane oxidation will most likely not compete with methanol carbonylation (even though ethane is a very cheap and attractive raw material) because of the low ethane conversions, product inhibition problems, and a large variety of by-products. 

In the late 1990s BP introduced a new, more economic process using iridium as the catalyst - the CATIVA process. Since then many plants have been retrofitted for the use of this catalyst and new plants built are based on the new technology. 

As has happened with many catalytic processes, many years of research on the carbonylation of methanol has led to the discovery of a new catalytic system, now based on iridium. Since the early patents of Monsanto it was known that iridium also forms active catalysts, but until the mid-1990s rhodium was the champion metal. Other metals are also active under similar conditions using the same iodide-based chemistry, such as nickel and palladium [122]. SHght, yet important, modifications by BP have made iridium the best catalyst now available in a system known as the CATIVA process. It is similar to the rhodium-based Monsanto process, which after 25 years of successfiil operation is gradually being replaced by the CATIVA process [123]. In 2003 four plants were in operation using this new catalyst... 

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