Bài viết trinh bày những kết quả bước đầu trong nghiên cứu sử dụng oxi hóa trực tiếp Benzen thành Phenol trên xúc tác V-W-Oxit/SiO2 và nghiên cứu ảnh hưởng của hơi nước đến quá trình oxy hóa Benzen.
NGHIEN CQU ANH HUONG CUA HOI NaOC DEN QUA TRINH OXI HOA TRLJC TIER BENZEN T H A N H PHENOL B A N G OXI TREN XUC T A C V-W-OXIT/SiOs Nguy§n Thi Bich Loc Khoa Hod - DHKHTN, DHQGHN MO DAU Phenol la mot nhiing boa chat quan ciia nganh cong nghiep hoa chat Ngay phenol chii yeu dudc san xuat b^ng phUdng phap Cumen PhUdng phap kha phiic tap, di tii nguyen lieu dau la benzen qua mot s6'giai doan trung gian va san pham thu dUdc ngoai phenol c6 axeton Viec tao axeton nhu mot ddng san pham vdi phenol da day gia cua phenol len cao Vi vay, viec tim mot phUdng phap mdi n h i m tdng hdp trUc tiep phenol tii benzen la rat c^n thie't Trong bai bao nay, chiing toi trinh bay nhiing ke't qua budc dau qua trinh nghien ciiu s\l dung oxi de oxi boa trUc tie'p benzen phenol tren xiic tac V-W-oxit/Si02 va nghien citu anh hUdng cua hdi nUdc den qua trinh oxi hoa benzen THirc NGHIEM - Xiic tac V-W-oxit/Si02 vdi phan % kho'i lUdng V2O5 va WO3 khac tong bam lUdng bai oxit la 5% tren chat mang SiOg dUdc dieu che'theo phUdng phap tbdng thUdng di tii dung dich cac muoi NH4VO3, (NH4)ioWi204i-5H20 va Si02 Tam dung dich NH4VO3 va ( N H ) I Q W I I H len Si02 roi c6 can, sau nung d nhiet 100°C gid va d 600°C gid se thu dUdc xiic tac V-W-oxit/SiOs- 177 - Qua trinh oxi hoa benzen b^ng oxi dUdc tien hanh he tho'ng thiet bi ddng cac chat tbam gia phan ling (d the khi) dUdc dim qua ong phan iing b^ng thach anh chiia xuc tac Phan ling dien theo sd do: H70.823 K ^ V-W-oxit/Si02 hidroquinon, phenol, p-quinon, axitmaleic, cacbon oxit, cacbon dioxit, san pham chinh gom: phenol (PhOH), hidroquinon (HQ) va benzoquinon (BQ) Ba chat dUdc goi la cac phenol Phan Ung dUdc thUc hien nhiing dieu kien sau: - Nhiet thUc hien phan ling: 823 K - Kho'i lUdng xiic tac: 0,2 gam - Ap suat rieng phan cua benzen P(CgHg): 5,6 kPa - Ap suat rieng phan ciia oxi P(02): 11,3 kPa - Ap suat rieng phan cua nUdc P(H20): 75,6 kPa - Ap suat rieng pb^n cua heli P(He): 8,8 kPa San pham phan ling dUdc phan tich bang sac ki long bieu lUc cao (HPLC) Shimazdu LC-IOAT vdi detectd UV-VIS va san pham (CO, CO2) Cling vdi oxi du dUdc phan tich tren may sac ki Shimazdu GC-8A vdi detectd TCD KET QUA VA THAO LUAN Chiing toi da tie'n hanh oxi hoa benzen tren xiic tac V-W-oxit/Si02 vdi phan % kho'i lUdng oxit vanadi va oxit vonfram khac tong ham lUdng hai oxit la kh6ng-doi va b^ng 5% kho'i lUdng tinh theo V2O5 va WO3 tren chat mang la Si02 Ke't qua cho thay xiic tac V-oxit 5%/ Si02 to c6 hoat tinh xiic tac cho qua trinh oxi boa benzen b4ng oxi nhUng bieu suat va chon loc tha'p Mat khac, xiic tac Woxit khong c6 boat tinh xiic tac dd'i vdi qua trinh oxi hoa benzen NbUng oxit dUdc tron l l n vdi boat tinh xiic tac tang ro ret 178 Dae biet dd'i vdi xiic tac V(4%)-W (l%)-oxit/Si02 chiing toi da quan sat dUdc boat tinh xiic tac dat gia tri cUc dai vdi ham lUdng san pham cac phenol 2,5% Tiep theo chiing t6i khao sat cac xiic tac c6 ty le ve kh6'i lUdng V2O5/WO3 la kh6ng doi va hkng 4/1, nhUng tong ham lUdng oxit tren chat mang (Si02) thay doi dan den ke't qua thu dUdc xiic tac chiia 3,5 % tong oxit/Si02 (V-W-oxit (3,5%)/Si02) cho boat tinh xiic tac cao nhat d6'i vdi qua trinh oxi hoa benzen vdi ham lUdng san pham cac phenol dat 4% Ke't qua chi d hinh Viec tang ham lUdng xiic tac hdn niia chi lam tang qua trinh oxi boa benzen CO va CO2 Tii d6 chiing t6i sii dung xiic tac V-W-oxit (3,5%)/Si02 cho nbuCng nghien ciiu tiep theo ;:^ c CO Đã 11 B X Tong ham lUdng oxit/Si02 (%) Hinh Anh hifdng cua ham luang oxit tr^n chat mang (Si02) den ham lucmg san phim (cac phenol) Chiing t6i da tien hanh nghien ciiu khao sat ben cua xuc tac Phan ling oxi hoa benzen tren xiic tac V-W-oxit (3,5%)/Si02 dUdc tien hanh thdi gian 7^ d 823 K Sau tiing khoang thdi gian b i n g (1 gid) san pham dUdc phan tich b^ng HPLC va GC Ke't qua dUdc chi d hinh 179 mmol.h-lg-1 Thdi gian (gid) Hinh Anh hudng th6i gian lam viec cua xuc tac den toe tao san phim (cac phenol) Trong thdi gian b^t d^u phan ling (< h) t6c tao t h a n h COx kha Idn, sau gid td'c tao COx giam deu dan va sau gid dat gia tri khdng doi Trong td'c tao cac phenol g^n nhU khdng doi gid Ket qua cho phep chiing t6i khang dinh ben cua xiic tac du de tien hanh nhiing nghien ciiu tiep theo Viec nghien ciiu cac dieu kien toi Uu cho phan iing oxi boa se dUdc de cap den cac bao cao sau Qua tham khao mot so' c6ng trinh da c6ng b6' [1-5] chiing toi dU doan sU c6 mat hdi nUdc hSn hdp phan ling c6 the anh hudng den qua trinh tao san pham Trong nghien ciiu nay, chiing t6i da khao sat sU anh hudng cua ye'u t6' den qua trinh oxi hoa benzen, ke't qua dUdc chi d hinh Khi khdng c6 mat hdi nUdc h6n hdp phan ling, chu yeu xay qua trinh oxi hoa benzen t h a n h CO va C02Khi lUdng hdi nUdc dUa vao vUdt qua 30 kPa, toe d6 tao t h a n h CO va CO2 giam ban va toe tao cac phenol tang cung vdi vi^c tang ap suat rieng phan cua hdi nUdc 180 100 • \ OH c 60 40 Ham luang cac phenol ;:^ "x< tie C S c CO + C02 20 —1 10 20 30 1-— 40 1 50 60 70 2, B 80 X PH2O (kPa) Hinh Anh hudng ap suat rieng phan cua hoi nude den ham lugmg san ph^m K^T LUAN Qua nghien ciiu chiing toi da tim dUdc mot xiic tac mdi V-W-oxit (3,5%)/Si02 to c6 boat tinh xiic tac cao nhat dd'i vdi qua trinh oxi boa benzen t h a n h cac phenol b i n g oxi phan tii (vdi bam lUdng san pham cac phenol dat %) Do ben cua xiic tac dam bao cho nhiing nghien ciiu dong hoc cua qua trinh oxi hoa benzen Ham lUdng cac san pham chinh tao tang ddng bie'n vdi hdi nude CO mat hdn hdp phan iing chiing to r i n g sU c6 mat cua hdi nude vdi nong cao hdn hdp phan iing la mot nhiing yeu t6'quye't dinh den bieu suat tdng hdp phenol Noi dung nghien ciiu ciia chiing toi dang tap trung vao hUdng va cac ke't qua nghien ciiu sau hdn se dUdc cong bo' cac cong trinh tiep theo nhiim giai thich ro hdn cd che cua qua trinh 181 TAI LI$U THAM KHAO M Iwamono, J I Hirata, K Matsukami and S Kagawa, J Phys Chem., 87, 903 (1983) E Suzuki, K Nakashiro, Y Ono, Chem lett., 953 (1988) R Burch and C Howitt, Appl Catal., 98, 33 (1993) G I Panov, et a l Chemical Week, 159, 11 (1997) I Yamanaka, K Otsuka, et al., ICC 121b in Granada, D-10, (2000) INFLUENCES OF THE WATER VAPOR ON THE DIRECT OXIDATION OF BENZENE TO PHENOLS WITH O2 OVER V-W-OXIDE/SIO2 CATALYSTS V-W-oxide/Si02 catalyst was active for the partial oxidation of benzene to phenols (phenol, hydroquinone and benzoquinone) with O2 A synergisn of V-oxide and W-oxide on the partial oxidation of benzene was observed, the yield of phenols was dramaticaly enhanced by addition of water vapor 182 ... ON THE DIRECT OXIDATION OF BENZENE TO PHENOLS WITH O2 OVER V-W-OXIDE/SIO2 CATALYSTS V-W-oxide/Si02 catalyst was active for the partial oxidation of benzene to phenols (phenol, hydroquinone and... trinh oxi boa benzen t h a n h cac phenol b i n g oxi phan tii (vdi bam lUdng san pham cac phenol dat %) Do ben cua xiic tac dam bao cho nhiing nghien ciiu dong hoc cua qua trinh oxi hoa benzen Ham... V-W-oxit/Si02 hidroquinon, phenol, p-quinon, axitmaleic, cacbon oxit, cacbon dioxit, san pham chinh gom: phenol (PhOH), hidroquinon (HQ) va benzoquinon (BQ) Ba chat dUdc goi la cac phenol Phan Ung dUdc