SÃntese e caracterizaÃÃo de silicoaluminofosfatos para a produÃÃo de olefinas leves a partir do dimetilÃter

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Methanol/dimethylether to olefin (MTO) process provides an additional route for production of ethylene and propylene for the chemical industry. This process has some advantages over the current ethylene and propylene production process, the steam cracking of liquefied natural gas, naphtha or other light fractions of petroleum, because MTO can provide a wider and more flexible range of ethylene to propylene ratio than stream cracking to meet market demand. Also, methanol can be produced from synthesis gas, which can be made from any source of carbon-containing materials such coal petroleum residue, biomass and natural gas. There have been many catalysts of silicoaluminophosphate type examined for the MTO process. However, SAPO-34 was believed to be the best catalyst in terms of conversion, activity and selectivity to light olefins. This work had the objective of synthesize three catalysts of SAPOs type, to verify the influence of its structures and the metal incorporation on DME conversion to olefins. Analysis of textural characterization by nitrogen adsorption (BET), X ray diffraction (DRX), scanning electron microscopy (SEM), thermogravimetric analysis, acidic properties and atomic absorption spectrometry were relevant to the complete characterization and understanding of the catalytic properties of the prepared materials. Within the catalytic tests, it was verified the influences of the as synthesized materials properties about the conversion of DME, selectivity and activity. Among the tested catalysts (SAPO-44, SAPO-34 and NiSAPO-34), SAPO-34 presented the best results in terms of conversion (75%), with selectivity towards light olefins of about 25%. The metal incorporation on the molecular sieve structure was important, once it was verified a decrease on the deactivation rate and a relevant increase on the selectivity towards ethene, resulting on a C2 =:C3 = molar ration of 1,7. A Langmuir-Hinshelwood kinetic model of DME consumption on SAPO-34 was developed, leading to an activation energy of 29,7 kJ.mol-1

ASSUNTO(S)

eteno dimetilÃter dimethyl ether engenharia quimica sapo-34 propeno propene ethene sapo-34

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