Hydrocarbon cracking

If inert material is to be added, then ease of separation is an important consideration. For example, steam is added as an inert to hydrocarbon cracking reactions and is an attractive material in this respect because it is easily separated from the hydrocarbon components by condensation. If the reaction does not involve any change in the number of moles, inert material has no effect on equilibrium conversion. 

Hydrocarbon cracking Hydrocarbon feedstocks Hydrocarbon oils Hydrocarbon oxidation Hydrocarbon polymers... 

The price of acetaldehyde duriag the period 1950 to 1973 ranged from 0.20 to 0.22/kg. Increased prices for hydrocarbon cracking feedstocks beginning in late 1973 resulted in higher costs for ethylene and concurrent higher costs for acetaldehyde. The posted prices for acetaldehyde were 0.26/kg in 1974, 0.78/kg in 1985, and 0.92/kg in 1988. The future of acetaldehyde growth appears to depend on the development of a lower cost production process based on synthesis gas and an increase in demand for processes based on acetaldehyde activation techniques and peracetic acid. 

Methyl /-Butyl Ether. MTBE is produced by reaction of isobutene and methanol on acid ion-exchange resins. The supply of isobutene, obtained from hydrocarbon cracking units or by dehydration of tert-huty alcohol, is limited relative to that of methanol. The cost to produce MTBE from by-product isobutene has been estimated to be between 0.13 to 0.16/L ( 0.50—0.60/gal) (90). Direct production of isobutene by dehydrogenation of isobutane or isomerization of mixed butenes are expensive processes that have seen less commercial use in the United States. 

Naphtha desulfurization is conducted in the vapor phase as described for natural gas. Raw naphtha is preheated and vaporized in a separate furnace. If the sulfur content of the naphtha is very high, after Co—Mo hydrotreating, the naphtha is condensed, H2S is stripped out, and the residual H2S is adsorbed on ZnO. The primary reformer operates at conditions similar to those used with natural gas feed. The nickel catalyst, however, requires a promoter such as potassium in order to avoid carbon deposition at the practical levels of steam-to-carbon ratios of 3.5—5.0. Deposition of carbon from hydrocarbons cracking on the particles of the catalyst reduces the activity of the catalyst for the reforming and results in local uneven heating of the reformer tubes because the firing heat is not removed by the reforming reaction. 

For environmental reasons, burning should be smokeless. Long-chain and unsaturated hydrocarbons crack in the flame producing soot. Steam injection helps to produce clean burning by eliminating carbon through the water gas reaction. The quantity of steam required can be as high as 0.05—0.3 kg steam per kg of gas burned. A multijet flare can also be used in which the gas bums from a number of small nozzles parallel to radiant refractory rods which provide a hot surface catalytic effect to aid combustion. 

The hydrocarbon cracking operations that generate feed olefins generally do not produce sufficient isobutane to satisfy the reaction requirements. Additional isobutane must be recovered from cmde oil or natural gas Hquids or generated by other refinery operations. A growing quantity of isobutane is produced by the isomerization of / -butane [106-97-8]. 

The direct counter-current contact of a hot gas with a cool immiscihle liquid is effectively used in certain hydrocarbon cracking processes for the quenching of hot gases/vapors. Sometimes, the liquid used is oil and followed hy water quench, as is typical in ethylene plants cracking naphtha or other hydrocarbon as feed stock. 

Propane cracking is similar to ethane except for the furnace temperature, which is relatively lower (longer chain hydrocarbons crack easier). However, more by-products are formed than with ethane, and the separation section is more complex. Propane gives lower ethylene yield, higher propylene and butadiene yields, and significantly more aromatic pyrolysis gasoline. Residual gas (mainly H2 and methane) is about two and half times that produced when ethane is used. Increasing the severity... 

Example 5.6 Hydrocarbon cracking reactions are endothermic, and many different techniques are used to supply heat to the system. The maximum inlet temperature is limited by problems of materials of construction or by undesirable side reactions such as coking. Consider an adiabatic reactor with inlet temperature Tm. Then T z) < T, and the temperature will gradually decline as the reaction proceeds. This decrease, with the consequent reduction in reaction rate, can be minimized by using a high proportion of inerts in the feed stream. 

Repeat the analysis of hydrocarbon cracking in Example 5.6 with... 

Repeat the analysis of hydrocarbon cracking in Example 5.6 for the case where there is external heat exchange. Suppose the reaction is conducted in tubes that have an i.d. of 0.012 m and are 3 m long. The inside heat... 

Various other radiation-induced reactions have been studied for potential use in the industry on a pilot-plant scale. Among these may be mentioned hydrocarbon cracking (i.e., production of lower-molecular-weight hydrocarbons from higher-molecular-weight material), isomerization of organic molecules, and synthesis of labeled compounds with radioactive nuclei. When organic compounds are irradiated in the pure state or in aqueous solution, dimeric... 

Chromium zeolites are recognised to possess, at least at the laboratory scale, notable catalytic properties like in ethylene polymerization, oxidation of hydrocarbons, cracking of cumene, disproportionation of n-heptane, and thermolysis of H20 [ 1 ]. Several factors may have an effect on the catalytic activity of the chromium catalysts, such as the oxidation state, the structure (amorphous or crystalline, mono/di-chromate or polychromates, oxides, etc.) and the interaction of the chromium species with the support which depends essentially on the catalysts preparation method. They are ruled principally by several parameters such as the metal loading, the support characteristics, and the nature of the post-treatment (calcination, reduction, etc.). The nature of metal precursor is a parameter which can affect the predominance of chromium species in zeolite. In the case of solid-state exchange, the exchange process initially takes place at the solid- solid interface between the precursor salt and zeolite grains, and the success of the exchange depends on the type of interactions developed [2]. The aim of this work is to study the effect of the chromium precursor on the physicochemical properties of chromium loaded ZSM-5 catalysts and their catalytic performance in ethylene ammoxidation to acetonitrile. 

Hydrocarbon cracking is a first-order reaction. Neglecting pressure drop, find the specific reaction rate. 

A fairly large number of patents has been issued describing the application of aluminum-deficient Y zeolites in different areas of catalysis. Ultrastable Y zeolites have been used in the preparation of catalysts applied in hydrocarbon cracking, e.g. (94,95) hydrocracking, e.g. (96,97) hydrotreating, e.g. (98) and disproportionation, e.g. (99). 

In 1962 Mobil Oil introduced the use of synthetic zeolite X as a hydrocarbon cracking catalyst In 1969 Grace described the first modification chemistry based on steaming zeolite Y to form an ultrastable Y. In 1967-1969 Mobil Oil reported the synthesis of the high silica zeolites beta and ZSM-5. In 1974 Henkel introduced zeolite A in detergents as a replacement for the environmentally suspect phosphates. By 2008 industry-wide approximately 367 0001 of zeolite Y were in use in catalytic cracking [22]. In 1977 Union Carbide introduced zeolites for ion-exchange separations. 

Hydrocarbon Cracking Selectivities with Dual-Function Zeolite Catalysts... 

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