A refinery compares two zeolite catalysts for converting a heavy gas oil fraction into smaller hydrocarbons. Fig. 1 shows the pilot plant used for the test....
Question 1 Report
A refinery compares two zeolite catalysts for converting a heavy gas oil fraction into smaller hydrocarbons. Fig. 1 shows the pilot plant used for the test. In one run, 2.50 kg of feed is passed over catalyst A. Analysis shows that 18.0% by mass of the products is ethene. The process is carried out continuously so that the catalyst can be regenerated.
(a) State two conditions shown in Fig. 1 that are needed for this cracking reaction. [2]
(b) Complete the equation: C10H22 → C8H18 + ________. [2]
(c) Give two ways in which a catalyst changes a reaction. [2]
(d) Calculate the mass of ethene produced in the run using catalyst A. [2]
(e) Explain why ethene is removed from the products and collected separately. [2]
(f) Name the type of reaction when many ethene molecules join to form poly(ethene). [1]
(g) State why catalyst regeneration is needed in a continuous process. [1]
Answer Details
(a) The required conditions shown are a zeolite catalyst [1] and high temperature, 500 °C [1].
(b) \[\mathrm{C_{10}H_{22}\rightarrow C_8H_{18}+C_2H_4}\] The missing product is C2H4 [1]; this gives 10 carbon and 22 hydrogen atoms in total [1].
(c) A catalyst speeds up a reaction [1] and is not used up, remaining chemically unchanged at the end [1].
(d) \[\frac{18.0}{100}\times2.50\text{ kg}=0.450\text{ kg}\] ethene [2].
(e) Ethene is a useful chemical feedstock, particularly for making polymers [1]. Separating it gives a purer product and prevents it being mixed with fuel fractions [1].
(f) Joining many ethene molecules is addition polymerisation [1].
(g) Regeneration is needed because carbon, or coke, coats the catalyst and makes it less effective; the coating must be removed [1].
Download The App On Google Playstore
Everything you need to excel in your exams
