Alkylating process for alkyl benzenes

An alkylating process for alkyl benzenes to prepare an alkylate, including the following steps:

• a) an alkyl benzene having the following formula (I) and a first stream of alkylating agent being fed into a first reaction zone, contacting with a catalyst A, to produce a process stream I, wherein the alkylating agent is at least one selected from the group consisting of methanol, formaldehyde and dimethoxy methane,
• wherein, substituents Rs, when more than one exists, may be the same as or different from one another, each independently selected from the group consisting of C1-4 linear or branched alkyls, n represents the number of the substituent R and is an integer of 0, 1 or 2;
• b) the process stream I and a second stream of alkylating agent being fed into at least one second reaction zone, contacting with a catalyst B, to produce a process stream II;
• and
• c) the process stream II being fed into at least one third reaction zone, contacting with a catalyst C, to produce a process stream III containing an alkylate,
• wherein a reaction temperature in the first reaction zone is less than a reaction temperature in the third reaction zone,
• wherein at least one of the catalyst A, the catalyst B and the catalyst C is an alkali metal ion exchanged molecular sieve produced in line with a process including a step of contacting a molecular sieve with an alkali metal ion source to conduct ion-exchanging, wherein the molecular sieve is one or more selected from the group consisting of a X molecular sieve and a Y molecular sieve, and the alkali metal is a combination of K/Rb, a combination of K/Cs, a combination of Rb/Cs or a combination of K/Rb/Cs,
• wherein the reaction temperature in the first reaction zone is 320-385 degrees centigrade, a reaction temperature in the second reaction zone is 380-420 degrees centigrade, and the reaction temperature in the third reaction zone is 400-450 degrees centigrade, and
• wherein the alkylate is a compound having the following formula (II) and/or a compound having the following formula (III),
• wherein R and n in each formula (II) and (III) are as defined in the formula (I), respectively.