The present invention is a process for dehydrating an alcohol to prepare corresponding olefin(s), comprising: (a) providing a feed (A) comprising at least an alcohol having at least 2 carbon atoms, and preferably at most 5 carbon atoms, or a mixture thereof optionally water, optionally an inert component, in a dehydration unit, (b) placing the feed (A) into contact with an acidic catalyst in a reaction zone of said dehydration unit at conditions effective to dehydrate at least a portion of the alcohol to make an olefin or a mixture of olefins having the same number of carbon atoms as the alcohol, (c) recovering from said dehydration unit an effluent (B) comprising: an olefin or a mixture of olefins, water, undesired by-products including aldehydes and lighter products resulting from degradation of said aldehydes under the conditions of step (b), optionally unconverted alcohol(s) if any, optionally the inert component, wherein, said feed (A)-providing step (a) comprises adding an effective amount of one or more organic compound capable to reduce the undesired by-products by comparison with a non introduction of such compound, said organic compound being chosen among organic acids.

Described herein are solid acid catalysts and the methods for catalytically preparing ,-unsaturated carboxylic acids and/or esters thereof. In one aspect, a zeolite catalyst may be used. The catalyst may, in certain embodiments, be modified to improve the selectivity and/or conversion of a reaction. For instance, a catalyst may be modified by ion exchange to achieve a desirable acidity profile in order to achieve high level of conversion of reactants and selectivity for desirable products of the catalytic reaction. In another aspect, a variety of feed stocks (e.g., starting compositions) may be used including an -hydroxycarboxylic acid, an -hydroxycarboxylic acid ester, a -hydroxycarboxylic acid, a -hydroxycarboxylic acid ester, cyclic esters thereof (e.g., lactide), and combinations thereof.

Embodiments of catalyst systems and methods of synthesizing catalyst systems are provided. The catalyst system may include a core comprising a zeolite; and a shell comprising a microporous fibrous silica. The shell may be in direct contact with at least a majority of an outer surface of the core. The catalyst system may have a Si/Al molar ratio greater than 5. At least a portion of the shell may have a thickness of from 50 nanometers (nm) to 360 nm.

A method for producing a fluoride functionalized zeolite catalyst is described, having a F/Si molar ratio of 0.1:1-3:1. The method involves mixing a fluoride salt with zeolite components to form a gel, which is then hydrothermally treated and calcined. The fluoride functionalized zeolite catalyst may be used for cracking an olefin stream into ethylene, propylene, and butylene, with high selectivity towards propylene. The fluoride functionalized zeolite catalyst may be used for 50 or more hours with a stable conversion rate and low coke formation.

The present invention is a process for dehydrating an alcohol to prepare a corresponding olefin, comprising: (a) providing a composition (A) comprising at least an alcohol having at least 2 carbon atoms, optionally water, optionally an inert component, in a dehydration unit, (b) placing the composition (A) into contact with an acidic catalyst in a reaction zone of said dehydration unit at conditions effective to dehydrate at least a portion of the alcohol to make a corresponding olefin, (c) recovering from said dehydration unit an effluent (B) comprising: at least an olefin, water, undesired by-products including aldehydes and light products, optionally unconverted alcohol(s), optionally the inert component,
wherein, said composition (A)providing step (a) comprises adding an effective amount of one or more sulfur containing compound capable to reduce the undesired by-products by comparison with a non introduction of such sulfur containing compound. The component introduced at step (a) can be chosen from the group consisting of thiols, sulfides, disulfides.

A process and catalyst system is disclosed for producing para-xylene from a C.sub.8 hydrocarbon mixture comprising ethylbenzene and at least one xylene isomer other than para-xylene. The process modifies the conventional process by operating with a higher weight hourly space velocity, lower pressure and lower hydrogen partial pressure, which allows production of on-specification benzene product without penalty with respect to ethylbenzene conversion, para-xylene approach to equilibrium or xylene losses. The catalyst system comprises a first catalyst bed comprising a first zeolite having a constraint index from 1 to 12 and an average crystal size from 0.1 to 1 micron and a platinum hydrogenation component, and a second catalyst bed comprising a second zeolite having a constraint index ranging from 1 to 12 and an average crystal size of less than 0.1 micron and a rhenium hydrogenation component.

The present invention is a process for dehydrating an alcohol to prepare corresponding olefin(s), comprising: (a) providing a feed (A) comprising at least an alcohol having at least 2 carbon atoms, and preferably at most 5 carbon atoms, or a mixture thereof optionally water, optionally an inert component, in a dehydration unit, (b) placing the feed (A) into contact with an acidic catalyst in a reaction zone of said dehydration unit at conditions effective to dehydrate at least a portion of the alcohol to make an olefin or a mixture of olefins having the same number of carbon atoms as the alcohol, (c) recovering from said dehydration unit an effluent (B) comprising :

an olefin or a mixture of olefins, water, undesired by-products including aldehydes and lighter products resulting from degradation of said aldehydes under the conditions of step (b), optionally unconverted alcohol(s) if any, optionally the inert component,
wherein,
said feed (A)-providing step (a) comprises adding an effective amount of one or more organic compound capable to reduce the undesired by-products by comparison with a non introduction of such compound, said organic compound being chosen among organic acids.

The present invention relates to a catalyst for the conversion of oxygenates to olefins, wherein the catalyst comprises one or more zeolites of the MFI, MEL and/or MWW structure type and particles of one or more metal oxides, the one or more zeolites of the MFI, MEL and/or MWW structure type comprising one or more alkaline earth metals selected from the group consisting of Mg, Ca, Sr, Ba and combinations of two or more thereof, wherein the catalyst displays a water uptake of 9.0 wt.-% or less, as well as to a process for the production thereof and to its use, in particular in a process for converting oxygenates to olefins.

Described herein are solid acid catalysts and the methods for catalytically preparing ,-unsaturated carboxylic acids and/or esters thereof. In one aspect, a zeolite catalyst may be used. The catalyst may, in certain embodiments, be modified to improve the selectivity and/or conversion of a reaction. For instance, a catalyst may be modified by ion exchange to achieve a desirable acidity profile in order to achieve high level of conversion of reactants and selectivity for desirable products of the catalytic reaction. In another aspect, a variety of feed stocks (e.g., starting compositions) may be used including an -hydroxycarboxylic acid, an -hydroxycarboxylic acid ester, a -hydroxycarboxylic acid, a -hydroxycarboxylic acid ester, cyclic esters thereof (e.g., lactide), and combinations thereof.

A process and catalyst system is disclosed for producing para-xylene from a C.sub.8 hydrocarbon mixture comprising ethylbenzene and at least one xylene isomer other than para-xylene. The process modifies the conventional process by operating with a higher weight hourly space velocity, lower pressure and lower hydrogen partial pressure, which allows production of on-specification benzene product without penalty with respect to ethylbenzene conversion, para-xylene approach to equilibrium or xylene losses. The catalyst system comprises a first catalyst bed comprising a first zeolite having a constraint index from 1 to 12 and an average crystal size from 0.1 to 1 micron and a platinum hydrogenation component, and a second catalyst bed comprising a second zeolite having a constraint index ranging from 1 to 12 and an average crystal size of less than 0.1 micron and a rhenium hydrogenation component.