Designing heterogeneous catalysts for naphthalene isopropylation

2,6 di-isopropylnaphthalene is a plant growth regulator and it is used for the manufacturing of products intended to prevent sprouting of stored potatoes; despite that in the last decades it has been mainly produced as a precursor of the corresponding dicarboxylic acid (2,6-naphthalene dicarboxylic acid) which is, with ethylene glycol, the monomer for polyethylene naphthalate (PEN) polymerization. PEN results appealing for many uses for which PET is more commonly utilized; the most relevant, higher glass transition temperature (PEN 122°C, PET 80°C), higher Young’s modulus (PEN 5200 MPa, PET 3900 MPa), lower oxygen permeability (PEN 20 cm3/[m2*day*atm], PET 56 cm3/[m2*day*atm]) and lower thermal shrinkage (PEN 0,6%, PET 1,3%). This thesis reports of the study of the alkylation reaction of naphthalene with propylene, to get 2,6 di-isopropylnaphthalene. Operative conditions such as temperature and feed composition were optimized. The effect of parameters, such as catalyst size and inlet flow rate, on catalytic performance were studied. Part of the work was aimed at checking the presence of internal and external diffusion limitations. Several commercial catalysts have been tried on the bench-scale plant, both zeolites and amorphous silica-alumina materials. Desilicated zeolites were synthesized and tested as well, resulting in interesting catalysts for such reaction, with the need of further optimization of the synthesis procedure. ASA materials, as main catalysts of this project, were synthesized by means of wet impregnation and tested on the bench-scale plant. From the results is possible to hypothesize the presence of species like PBS-Al and PBS-Si within the ASA framework, that provide the catalyst with Brønsted acid sites with a zeolite-alike strength. The synthesized ASA catalysts show promising results, with high activity, but selectivity needs to be improved. Catalysts were characterized by means of XRD, n-butylamine titration and TGA (on used samples).