Process for preparing olefins by dehydrating alcohols with less side effects comprising addition of sulfur containing compounds

A process for dehydrating an alcohol to prepare one or more corresponding olefins, the process comprising:

• (a) forming an acidic catalyst selected from modified crystalline aluminosilicates of the Framework Type FER having Si/Al framework molar ratio greater than 20 and a ratio between strong acid sites and weak acid sites, S/W, lower than 1.0, the ratio S/W being measured by temperature-programmed desorption of ammonia and being determined by the ratio of the peak area of ammonia desorbed above 340° C. to that desorbed below 340° by:
• (1) providing a crystalline aluminosilicate of the Framework Type FER having an Si/AI framework molar ratio of greater than or equal to 20, and
• (2) treating said crystalline aluminosilicate of (1) to form the modified crystalline aluminosilicate of the Framework Type FER having the Si/Al framework molar ratio greater than 20 and the ratio between strong acid sites and weak acid sites, S/W, lower than 1.0 by at least one treatment step selected from:
• (i) contacting said crystalline aluminosilicate of the Framework Type FER with a solution containing one or more organic compounds, wherein each of the one or more organic compounds comprises one or more —CO2H, —SO3H, or —SO4H groups or salts thereof, and wherein a concentration of each of the one or more organic compounds in the solution containing the one or more organic compounds is in a range of from 1×10−4 Molar (M) to 10 M;
• (ii) applying partial ion exchange to said crystalline aluminosilicate of the Framework Type FER (iii) selectively poisoning strong acid sites of the crystalline aluminosilicate of the Framework Type FER:
• or (iv) a combination thereof:
• (b) introducing into a dehydration unit containing metallic sites a feed (A) comprising one or more alcohols having at least 2 carbon atoms, optionally water, and optionally an inert component, and one or more sulfur containing compounds in an amount of from 0.5 wt ppm to 20 wt ppm of the total content of the feed (A),
• (c) contacting the feed (A) with the acidic catalyst in a reaction zone of the dehydration unit at conditions effective to dehydrate at least a portion of the alcohol to make a corresponding olefin or mixture of olefins,
• (d) recovering from the dehydration unit an effluent (B) comprising an olefin or mixture of olefins, water, undesired by-products including aldehydes, H2, CO, CO2, and CH4, optionally one or more unconverted alcohols, and optionally the inert component, and
• (e) determining the amount of the one or more sulfur containing compounds in the feed (A) introduced into the dehydration unit at (b) by:
• performing (c) with a feed (A) not comprising said one or more sulfur containing compounds, measuring an amount of the undesired by-products in the effluent (B) recovered at (d), and increasing the amount of said one or more sulfur containing compounds until the amount of the undesired by-products in the effluent (B) recovered at (d) is less than 4 wt %.