Preparation of high purity propane from liquefied petroleum gas in a fixed bed by removal of sulfur and butanes

• High purity propane was prepared from LPG in a fixed bed.
• Sulfur compounds in LPG were removed by adsorption over zeolite 13X and NaY efficiently.
• Butanes (i-butane and n-butane) in LPG were removed by adsorption over activated carbon efficiently.

High purity propane was prepared from liquefied petroleum gas (LPG) in a fixed bed by removal of sulfur and butanes (i-butane and n-butane). First, sulfur compounds were removed from LPG by fixed bed adsorption over three commercial zeolites (13X, NaY and 5A). Then, adsorption dynamics of propane, i-butane and n-butane on activated carbon were investigated by evaluating effects of the feed flow rate, bed length and temperature on breakthrough curves. Breakthrough curves for sulfur, propane and butanes adsorption were analyzed by Yoon–Nelson model. The experimental results indicated that zeolite 13X and NaY presented better desulfurization performance than zeolite 5A at the temperature of 303 K, feed flow rate of 20 mL/min and bed length of 15 cm. Breakthrough curves for sulfur, propane and butanes fitted relatively well to Yoon–Nelson model. The Yoon–Nelson model is strongly valid for breakthrough curves of n-butane, with all correlation coefficient exceeding 0.96. Butanes were more selectively adsorbed on activated carbon than propane. The adsorption selectivity of activated carbon for these three adsorbates decreased in the order of n-butane > i-butane > propane. Activated carbon had been proved to be a desirable adsorbent to remove butanes from LPG to prepare high purity propane under experimental conditions.

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