Bipin V. Vora

Economic route for natural gas conversion to ethylene and propylene

Publisher Summary The major component of natural gas is methane, which can be converted into methanol. Methanol is an important industrial intermediate in the manufacture of a number of products such as formaldehyde, acetic acid, and methyl tertiary butyl ether (MTBE). Methanol can also be used as a transportation fuel, but its use has been limited because of its other properties, such as its high water solubility and its blending vapor pressure. Natural gas can be converted to olefins with the help of GTO process. The first step in the process is the conversion of natural gas to methanol followed by the UOP/Hydro methanol to olefins (MTO) process using UOPs unique silicoaluminophosphate (SAPO)-34 catalyst. The primary products are ethylene and propylene. The processes most widely used in the conversion of natural gas to methanol include (1) ICI low-pressure methanol process, (2) Lurgi two-step reforming, and (3) Haldor Topsoe two-step reforming process.

Production of linear alkylbenzenes

Linear alkylbenzene technology has almost completely replaced the older branched alkylbenzene technology for production of surfactants due to improved biodegradability and cost-effectiveness. The technology of choice today is dehydrogenation of n-paraffins to n-olefins followed by benzene alkylation to produce linear alkylbenzene. Solid acids catalyst-based systems are emerging to slowly replace hydrofluoric acid units in order to ensure environmental safety and improve economics. Numerous materials have been evaluated as solid acid catalysts for this alkylation process including zeolites, clays, various metal oxides, and supported aluminum chloride. At this time, only the UOP Detal technology has been commercialized. Because of ongoing fundamental studies on reaction mechanism and catalyst properties, significant progress is being made to improve the selectivity, catalytic stability, and long-term stability of these solid acids under commercial operating conditions.

Development of Dehydrogenation Catalysts and Processes

Catalytic dehydrogenation plays an important role in production of light (C3–C4 carbon range), detergent range (C10–C13 carbon range) olefins and for ethylbenzene dehydrogenation to styrene. During the World War II, catalytic dehydrogenation of butane over a chromia–alumina catalyst was practiced for the production of butenes that were dimerized to octenes and hydrogenated to octanes to yield high-octane aviation fuels. The earlier catalyst development employed chromia–alumina catalyst and more recent catalytic developments use platinum or modified platinum catalysts. Dehydrogenation is a highly endothermic process and as such is an equilibrium limited reaction. Thus important aspects in dehydrogenation entail approaching equilibrium or near-equilibrium conversion while minimizing side reactions and coke formation.

Most recent developments in ethylene and propylene production from natural gas using the UOP/Hydro MTO process

Abstract The UOP/Hydro MTO Process utilizes a SAPO-34-containing catalyst that provides up to 80% yield of ethylene and propylene at near-complete methanol conversion. The process has great flexibility to produce a product with a range of ethylene/propylene ratios, depending on the operating conditions used. This paper will discuss recent improvements related to the technology which have increased the carbon selectivity from methanol to ethylene-plus-propylene to about 85–90%.

16 Converting natural gas to ethylene and propylene using the UOP/HYDRO MTO process

Abstract The development of new ways to convert natural gas, especially methane, to higher valued products is one of the keys to increasing the utilization of this abundant natural resource. The combination of methanol production using state-of-the-art mega methanol technology with the new methanol-to-olefins (MTO) process developed by UOP and Norsk Hydro provides an economically attractive route from natural gas to ethylene and propylene. These light olefins are feedstocks for a wide variety of high-value petrochemicals and polymers. The UOP/HYDRO MTO process utilizes a SAPO-34-containing catalyst, which provides up to 80% yield of ethylene and propylene at near-complete methanol conversion. The process has great flexibility to produce a product with a range of ethylene/propylene ratios, depending on the operating conditions used. A major end use for both ethylene and propylene is the production of polyolefins. Since polymerization catalysts are very sensitive to a wide variety of poisons, trace by-products in the MTO light oflefin effluent have been identified. Conventional treating methods have been shown to be effective for removing these by-products to the specification levels required for olefin polymerization processes. This work has shown that the ethylene and propylene produced by the MTO process is a suitable feedstock for olefin polymerization.