Todays Industrial Methanol Synthesis

However, lower-temperature operation would thermodynamically hinder CO formation via methanol decomposition and rWGS. A low CO content is desired for MSR-PEMFC combinations (see Section 5.3.7). To that end, the development of catalysts active at lower temperatures still remains the central goal of methanol catalysis research. 

In 2009, worldwide production of methanol was around 40 million metric tons. Although this amount represents only 0.01% of the worldwide gasoline production, it is nearly equivalent to the total biodiesel and bioethanol production [11], From this number, it is clear that a large-scale replacement of gasoline by methanol as fuel would require an enormous increase of worldwide methanol synthesis capacities. Today, chemical intermediates dominate methanol consumption. Formaldehyde a platform molecule for the synthesis of polymer resins - is responsible for nearly half of the total demand. Acetic acid, MTBE, and methyl methacrylate - a monomer -constitute another 25% [7, 12]. Direct fuel and additive usage accounts for 15% of demand but is expected to rise. 

Methanol synthesis plants utilizing the low-pressure process currently operate at capacities of 2 x 105 to 2 x 106 metric tons per year [15]. Such installations are composed of a synthesis gas production unit, the actual methanol synthesis reactor, and a separation and purification section. The production and purification of synthesis gas accounts for 50%-80% of the total cost of methanol production, with the remaining cost associated with the actual synthesis and purification of methanol [2, 8], Although a variety of carbonaceous feedstocks can be transformed into synthesis gas, the steam reforming of natural gas (Equation [4]) is by far the most common option, especially for large plants [2, 15-16]  

Gas mixtures with a modulus value, M (Equation [5]), of around 2 satisfy the stoichiometric requirements  

Countries with large domestic coal reserves, such as China and South Africa, rely primarily on coal gasification to produce synthesis gas. This synthesis gas is hydrogen deficient (M 2) and must undergo a further water-gas shift (WGS) step to yield a C02-rich mixture [2]. Methanol synthesis from C02 and C02-rich mixtures provides special catalyst and reactor design challenges, which will be further discussed in more detail. 

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Methanol production today is not a sustainable process but is part of a petrochemical route for conversion of fossil carbon into chemicals and fuels (see Section 5.3.3). It has to be emphasized that a one-to-one upscaling of existing industrial methanol synthesis capacities for fuel production is not useful. This is mainly because the current industrial process has not been developed and optimized under the boundary conditions of conversion of anthropogenic C02, but rather for synthesis gas feeds derived from fossil sources such as natural gas or coal. The switch to an efficient large-scale methanol synthesis with a neutral C02 footprint is still a major scientific and engineering challenge, and further research and catalyst and process optimization is urgently needed to realize the idea of a sustainable methanol economy. ... 

Dimethyl ether forms as condensation side product of the methanol synthesis from CO/H2. Today, the greatly improved selectivity of modern methanol catalysts has reduced this side-product formation to such an extent that deliberate production of dimethyl ether from methanol at heterogeneous alumina or aluminosilicate contacts is carried out industrially. 

In Haldor Tops0e s ammonia and methanol synthesis processes a series of adiabatic beds with indirect cooling between the beds is normally used, at least in large plants. In smaller plants internally cooled reactors are considered. In ammonia synthesis, the Tops0e solution is today the so-called S-200 converter (Fig. 7) and L6j. This converter type, which is a further development of the S-100 quench-type converter, was developed in the mid seventies the first industrial unit was started up in 1978, and today about 20 are in operation or on order. Both the S-100 and the S-200 reactors are radial flow reactors. The radial flow principle offers some very specific advantages compared to the more normal axial flow. It does, however, also require special catalyst properties. The advantages of the radial flow principle and the special requirements to the catalyst are summarized in Table 5. 

The man-made catalysts, mostly solids, usually aim to cause the high-temperature rupture or synthesis of materials. These reactions play an important role in many industrial processes, such as the production of methanol, sulfuric acid, ammonia, and various petrochemicals, polymers, paints, and plastics. It is estimated that well over 50% of all the chemical products produced today are made with the use of catalysts. These materials, their reaction rates, and the reactors that use them are the concern of this chapter and Chapters 19-22. 

Mankind has produced acetic acid for many thousand years but the traditional and green fermentation methods cannot provide the large amounts of acetic acid that are required by today s society. As early as 1960 a 100% atom efficient cobalt-catalyzed industrial synthesis of acetic acid was introduced by BASF, shortly afterwards followed by the Monsanto rhodium-catalyzed low-pressure acetic acid process (Scheme 5.36) the name explains one of the advantages of the rhodium-catalyzed process over the cobalt-catalyzed one [61, 67]. These processes are rather similar and consist of two catalytic cycles. An activation of methanol as methyl iodide, which is catalytic, since the HI is recaptured by hydrolysis of acetyl iodide to the final product after its release from the transition metal catalyst, starts the process. The transition metal catalyst reacts with methyl iodide in an oxidative addition, then catalyzes the carbonylation via a migration of the methyl group, the "insertion reaction". Subsequent reductive elimination releases the acetyl iodide. While both processes are, on paper, 100%... 

The synthesis of acetaldehyde, essentially intended for conversion to acetic acid, was the main outlet for ethanol until a few years ago. The industrial development of methanol carbonylation to acetic arid has relegated this application to the background. Ethanol is chiefly used today as a solvent and for the preparation of esters (ethyl acetate, ethyl chloride). It is also employed in cosmetics and pharmaceuticals. 

Catalytic processes today dominate the production of sulfuric acid, ammonia, methanol, and many other industrial products. The cracking of mineral oils, the hydrogenation, transformation, and synthesis of hydrocarbons are almost all centered around catalytic conversions carried out with many different catalysts including some of highly specific action. Many more catalyzed reactions are being carried out in batch processes and in continuous operations, in heterogeneous and in homogeneous systems. 

Until about 1930, Boyle s methanol-making method remained in use. Today, it is made from synthesis gas. When steam reacts with coal, oil, or natural gas, it forms a mix of hydrogen and carbon monoxide. This mixture is known as syngas, and it can be reacted with a zinc-oxide/chromium-oxide catalyst to make methanol. Methanol is used as a gasohne additive (it makes the gas b um better), as an industrial solvent, and, of course, as an ingredient in windshield washer fluid. 

The above three applications represent the quasi totality of the CO2 used in the chemical industry till today. As Table 39.2 shows, additional amounts of CO2 are used in the synthesis of methanol and some organic carbonates and polymers. 

The first commercial plant for the chemical production of acetic acid came on line in 1916. Qearly, this was the beginning of the expanding market for acetic add as an important commodity chemical in industry (Agreda and Zoeller 1993). Chemical synthesis of acetic acid is dependent upon petrochemicals from nomenewable crude oil resources. There are three major processes in use today oxidation of acetylene-derived acetaldehyde, catalytic butane oxidation, and the carbonylation of methanol (the Monsanto process Agreda and Zoeller 1993). Production hy the Monsanto process provides the major source of glacial acetic add used in industry worldwide. In the United States, chemical synthesis of acetic acid was reported as 2.34 x 10 t/year in 1995 (Kirschner 1996), which demonstrates the importance of acetic acid as a commodity chemical in industry. 

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