| X zeolite as a kind of important synthetic porous materials can be better applied to chemical industry area by modifying its surface. Styrene is the most simple unsaturated aromatic and extremely important basic chemical raw material. It has wide application in dyes, pharmaceutical, pesticide, mineral, and other industries. Traditional production methods which make 90% amount of styrene usually has a high dependence on fossil resource and a more and more weaker competitiveness, and has a lot of disadvantages such as severe corrosion, serious pollution and high energy consumption. Using modified 13X zeolite as the catalyst of side alkylation of toluene with methanol to product styrene not only greatly reduces the cost of the raw materials but also opens up new avenues for comprehensive utilization of coal products. So it has good prospects for industrial applications.This article modified the surface and microporous of 13X zeolites by ion exchange, impregnation or evaporated loading and so on and tested their catalysis activities for side alkylation of toluene with methanol. This article also investigated the effects of WHSV, raw material ratio, carrier gas flow rate, reaction temperature on reaction progress. This article tested acid-base properties on zeolite surface and polymorphs by CO2-TPD、NH3-TPD、XRD、 FT-IR and so on. The results of NH3-TPD showed that loading chloride would enhance acid of zeolites. After exchanged by K ion the Na-type zeolite 13X could get weaker acid strength but more acid sites. The results of CO2-TPD demonstrated that KX(n) got a new moderate base desorption peak contrast to 13X, whose area becoming larger with the increasing of exchange degree. This article also studied effects of loading methods, loading amounts, loading species etc on the catalysis activity of catalyst.The way of preparing catalysts had significant effects on catalysis activities. After loaded MgO by rotary evaporating, the zeolite becoming MgO/13X got stronger base and a side alkylation conversion of 5%, side alkylation selectivity of 75% under 500℃. Compared to repeatedly exchange method with no roasting under low temperature, ion exchange with batch roasting could got better catalysis activity and higher exchange degree while reaching 88% after 5 times. The best reaction temperature of MgO/KX was 440℃, when conversion was 12.2% and side alkylation selectivity was 90%. To secondary load H3BO3 on MgO/KX, the better loading method was co-impregnation followed by rotary evaporating. When MgO loading amount 5%(W), Mg:B=1:1, carrier gas flow rate 150mL/min, WHSV=0.63h-1,raw ratio 1:1, the side alkylation selectivity could keep more than 90% under each temperature and conversion reached 15.3% best while styrene content keeping more than 50% before 460 ℃ and being 67.5% best. MgO-2B2O3/KX had catalysis activity with conversion 18.3% and selectivity 90% under 460℃.Reaction conditions also had important influences on catalysis activities. This article took KX catalyst for example to study catalysis activity under different conditions. The conversion of toluene could reach 25.1% when toluene:methanol ratio being 1:3. The side alkylation yield reached extreme of 15.7%(base on methanol) when toluene:methanol ratio was 5:1. With the increasing of WHSV the side alkylation yield decreased after the first increasing to 8% at 0.79h-1 while the content of styrene always rose and reached 31% at 1.26h-1. The conversion reached extreme 10.2% when carrier gas flow rate increasing to 150mL/min, while the selectivity and content of styrene continuous rose and reached 84.5% and 27% respectively.This article completed modifying 13X zeolite and studied the effects of preparation condition and reaction condition on activity of catalysts. The results showed that the catalyst had well activity and nice side alkylation selectivity and good prospects for industrial applications. |
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