[Hk112] Tong Hop

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1 MC LC TNG HP BIODIESEL ............................................................................................................... 2 NHT NG HC ............................................................................................................... 13 CN CARBON CONRADSON .................................................................................................. 18 IM CHP CHY CC H .................................................................................................... 24 O T TRNG BNG PYCNOMETER ................................................................................... 27 NG CHNG CT ASTM ................................................................................................... 30 IM CHP CHY CC KN ................................................................................................... 38 O T TRNG BNG HYDROMETER................................................................................... 43 2 BI 1 TNG HP BIODIESEL I.MC CH -Gip sinh vin hiu r hn v nhin liu sinh hc -Tip cn phng php sn xut Biodiesel truyn thng II.C S L THUYT 1.Biodiesel -Biodiesel l cht lng c mu vng h phch, c nh ngha l cc monoalkyl ester ca ccacidbomchditccngunnguynliucthtisinhcnhccloidu thc vt, m ng vt.-Du thc vt v m ng vt l cc ngun cha cc acid bo c mch hydrocarbon khc nhau,linktviphntglycerinebnglinktester.Vicsdngtrctipdum lm nhin liu cho ng c gp phi mt s vn nh: -Nhin liu c nht cao (cao hn 11 - 17 ln so vi nhin liu diesel thng thng). nht cgi tr tu thuc vo di v bt bo ho ca cc phn t. nht cao gy ra mt s bt n cho ng c nh qu trnh phun nhin liu khng u n, c bit nhit thp lm cho ng c hot ng khng n nh. -bayhicadumrtthpnnchngkhchyhontonvhnhthnhnn mui bm vo vi phun ca ng c. -C 4 phng php c s dng gii quyt vn nht cao ca cc triglyceride: -Pha long 1 phn du m vi 3 phn nhin liu diesel -Vi nh tng ho vi cc ru mch ngn nh methanol v ethanol-Nhitphn(crackingnhit)toraalkane,alkene,acidcarboxylicvcchpcht thm; bao gm c cracking s dng cht xc tc to ra alkane, alkene, cycloalkane v alkylbenzene. 3 -Transesterho:csdngthngdngnhtnhmchuyndumngthcvt thnhnhinliubiodiesel(hnhpmonoalkylestercaccacidbo)sdng c cho ng c. 2.Phn ng transester ho a.Khi nim -Transester ho l phn ng chuyn ho ester bng cch phn ct phn t triglyceride, ly i phn t glycerine v thay th bng nhm chc alkyl ca ru. Cc xc tc c s dngcho phn ng transester ho l base(NaOH, KOH, CH3ONa),acid (H2SO4, HCl) v enzyme lipase. Ru thng c s dng l methanol, to sn phm l cc methyl ester ca acid bo vi chiu di ca mch alkyl l 12- 22 nguyn t carbon. Nc, cht xc tc, triglyceride v ru d cng vi ph phm l glycerine phi c loi ra khi hn hp sau phn ng thu c biodiesel. Glycerine c tinh ch l snphmcgitrtrongcngnghipmphm,thcphmvnhiungnhcng nghipkhc.Transesterhocxemllachnttnhtchuynhodum ng thc vt thnh nhin liu s dng c (biodiesel) v:-Cctnhchtvtlcaalkylesterrtgingvitnhchtvtlcanhinliu diesel.Hnna,methylhocethylestercaccacidbocthchytrctip trong cc ng c diesel thng thng m khng yu cu phi ci tin ng c v khng hnh thnh cn lng.-Quy trnh thc hin tng i ngin nn ddng p dng vo sn xut trong cng nghip.-To ra ph phm glycerine c nhiu ng dng trong cc ngnh cng nghip Trong bi th nghim ny, ta s dng phng php transester ho cc triglyceride ca du thc vt bng methanol vi s c mt ca xc tc base tng hp biodiesel. 4 b.C ch -C ch phn ng c s dng xc tc base: CchpchthohcctnhbasenhNaOH,KOH,CH3ONalxctcthng dng trong phn ng transester ho. Ru phn ng vi xc tc base to ra anion alkoxide RO- v proton H+. Tc nhn i nhn alkoxide tn cng vo nguyn t carbon ca nhm carbonyl, hnh thnh nn hp 5 cht trung gian c cu trc t din. Sau , cu trc ny sp xp li thnh alkyl ester v anion diglyceride tng ng. Anion diglyceride ny tc dng vi BH+ to ra phn tdiglyceridevgiiphngrabaseBtiptcthamgiaxctcphnng.Cc diglyceride v monoglyceride cng c c ch phn ng tng t hnh thnh nn hn hp alkyl ester v glycerine. B: xc tc base R: gc alkyl ca ru R1, R2, R3: mch hydrocarbon ca cc acid bo 6 -Cc alkoxide ca kim loi kim nh CH3ONa l cht xc tc rt mnh, cho hiu sut cao (> 98 %) trong thi gian ngn (30 pht) d c s dng nng thp (0,5 % mol). -Chtxctcvruphidngkhankhicchovohnhpphnng(tng lng nc phi t (0,1 0,3) % khi lng hoc t hn) v nc thc y phn ng thuphnalkylesterthnhacidbotdovsauhnhthnhxphng.K2CO3 c s dng nng 2 % hoc 3 % mol cho hiu sut thu alkyl ester cao v hn ch c s hnh thnh x phng v n gip to thnh mui bicarbonate thay v to ra nc. c.u im v nhc im -u im: Tc phn ng nhanh hn khong 4 000 ln khi so snh vi phn ng xc tc acid. -Nhc im: Xc tc base ch c dng cho cc loi du tng i sch, hm lng acid bo t do nh hn 1 %. Khi hm lng acid bo t do ln hn 1 %, hiu sut ca phn ng gimvacidbotdophnngvixctcbase(KOH,NaOH)hnhthnhnnx phng. X phng ny gy kh khn cho qu trnh thu hi glycerine v lm gim ng k hiu sut phn ng. Hm lng nc trong du m cng nh hng n hiu sut hnh thnh alkyl ester v nc nhiu lm phn ng x phng ho din ra mnh. III. DNG C V HO CHT 1.Dng c -Bnh cu 3 c 500 ml(1) -Sinh hn nc (1) -Nhit k 100 oC (1) -ng ong 100 ml (2) -Phu chit 500 ml (1) -Becher 500 ml (1) -Becher 250 ml (1) -Cc ng nc thi (1) 7 -Pipette 1 ml (1) -Bp in, t (1) -C t (1) -Phu (1) -Bnh nc ct(1) 2.Ho cht -NaOH cng nghip -H3PO4 m c -Du thc vt -CH3OH IV. PHNG PHP TH NGHIM 1.Cch tin hnh -Dng ng ong 100 ml ly 250 ml du thc vt cho vo bnh cu 3 c. Lp thit b nh hnh v. 8 -Trongkhichchonhitduln60 oC,cnchnhxckhong1,6875gNaOHcng nghip vo becher 250 ml, sau cho 62,5 ml CH3OH vo. Khuy cho NaOH tan trong CH3OH. Sau khi NaOH tan ht, cho dung dch vo bnh cu 3 c. Cn thn v CH3OH rt c. -Thc hin phn ng transester ho trong 1,5 h. Lu phi n nh nhit 60 oC. -Saukhiphnngxong,hnhpvophuchit.Chnkhihnhpphnphar rng, chit tch phn glycerine. -Phn biodiesel th c em i ra. Qu trnh ra gm 3 nc. Nc 1: dng pipette 1 ml ht 0,5 ml H3PO4 m c cho vo 65 ml nc ct Nc 2 v 3: dng nc ct. Cc ln ra l nh nhau v tin hnh nh sau: biodiesel th c cho vo becher 500 ml, sau cho nc ra vo, ln bp t khuy khong 3 pht sau chovo phu tch. Phn nc pha di c tch ra. -Sau ln ra cui cng, biodiesel c sy 110 oC trong 1 h. Gi mu bi sau o cc ch tiu cht lng sn phm. 2.nh gi sn phm biodiesel -Cn lng sn phm thu c nh gi hiu sut thu biodiesel. -Da vo th biu din s ph thuc ca % methyl ester trong hn hp sn phm vo nht ca hn hp (xem hnh) nh gi kh nng chuyn ho ca triglyceride trong du thc vt. -nh gi cht lng sn phm theo tiu chun ASTM D6751 theo cc ch tiu sau: -o nht ng hc ca biodiesel 40 oC theo ASTM D445 -o hm lng cn carbon ca biodiesel theo ASTM D4530 (tiu chun tng ng ASTM D189) 9 th biu din s ph thuc ca nht hn hp theo % methyl ester trong hn hp du V.KT QU 1.S liu th -Khi lng biodiesel thu c: 148,61 g -Th tch biodiesel thu c: 190 ml 2.Tnh ton a.Hiu sut thu biodiesel Thnh phn acid bo du u nnh gm: Tn (Cng thc ho hc)Khi lng mol phn t; g.mol-1% khi lng Acid -linoleic (C17H29COOH)27810 Acid linoleic (C17H31COOH)28051 Acid oleic (C17H33COOH)28223 Acid stearic (C17H35COOH)2844 Acid palmitic (C15H31COOH)25610 051015202530354045500 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100Lng methyl ester (%v/v)onh t (Cst)10 Khi lng mol phn t trung bnh ca cc acid bo trong du thc vt: 98 , 27710 4 23 51 1010 . 256 4 . 284 23 . 282 51 . 280 10 . 278=+ + + ++ + + +=EE=ii ixx MMg.mol-1 ViMi l khi lng mol phn t ca acid bo i; g.mol-1 xi l t l khi lng ring phn ca acid bo i Khi lng mol phn t ca triglyceride: 94 , 871 3 41 98 , 277 . 3 3 41 . 3 = + = + = M Mg g.mol-1 Khi lng mol phn t ca biodiesel:98 , 291 1 15 98 , 277 1 15 = + = + = M Mb g.mol-1 Khi lng ring ca du u nnh nhit phng: d = 0,92 g.ml-1 mso = 250. 0,92 = 230 g Xem du u nnh nguyn cht ch cha triglyceride: mg = mso = 230 g Khi lng Biodiesel thu c theo l thuyt: 95 , 22898 , 291 . 394 , 871 . 230. 3.= = =bg sobltMM mmg Hiu sut thu Biodiesel: % 91 , 64 % 100 .95 , 22861 , 148% 100 . = = =bltbttmmq b.Kh nng chuyn ho ca triglyceride trong du thc vt nht ng hc ca biodiesel o c l 4,099 cSt. Theo th, hn hp du sau phn ng cha 100 % th tch l methyl ester. 11 VI. BN LUN 1.Ti sao s dng acid phosphoric ra thay v s dng cc loi acid khc? -Trong thc t sn xut, ngi ta thng s dng H3PO4 ra dung dch biodiesel. Sn phm ph ca qu trnh l cc mui cha cc gc acid PO43-, HPO42-, H2PO4- . Ngoi ra, KOHthngcsdnglmxctc(dtgpiNaOH)vKOHhotanvi CH3OH d hn v mui phosphate kali c th c dng lm phn bn. V vy, kt hp vi quy trnh sn xut biodiesel, ta c th tn dng sn xut thm phn ln m khng phi thi b ra ngoi mi trng. 2.Ti sao ta khng th s dng thm nhiu methanol hn tng hiu sut qu trnh? Vai tr ca methanol d: -Chuyndchcnbngcaphnngtransesterhotheohngtosnphm.Vphn ng transester ho c tnh thun nghch nn lng tc cht cng d cng gip vic to sn phm thun li.-Gim nht ca h, gip cho kh nng o trn v tip xc pha gia cc thnh phn tc cht phn ng tt hn.Tuynhin,nulngmethanolcthmqunhiu,vaitrthhaikhngcnquan trngnadonhtcahrtkhccithinthm.Vimcchkinht,tas khng dng nhiu methanol. 3.Methanol l sn phm c hi nhng ti sao ngi ta vn dng methanol trong sn xut biodiesel? Ngoi kh nng phn ng, methanol cn nhiu u im so vi cc ru khc: -Gi thnh thp hn (tnh trn 1 mol : lng ru cn dng c xc nh bi t l mol ru : du) -Khilng(vthtch)methanolcndngthphndokhilngmolphntca methanol thp hn cc ru khc (trong khi khi lng ring khng khc nhau nhiu). - thu c biodiesel vi hiu sut cao (n 99,7 %), ngi ta phi dng d ru. Lng ru d phi c tch ra v quay tr li phn ng nhm gim chi ph sn xut v khng gy c hi mi trng. Methanol c nhit si thp (65 oC) nn d c tch ra khi hn hp phn ng hn. Thm vo , khi c tch ra, ru lun cha nc. Methanol 12 c th d dng tch khi nc bng nhng phng php chng ct thng thng. Nhng ru khc nh ethanol v iso-propanol to vi nc hn hp ng ph nn gy kh khn cho vic tch nc. 4.u im ca biodiesel so vi cc nhin liu khc t du m: Biodiesel c vi u im vt tri so vi nhin liu diesel t du m nh:-c sn xut t ngun nguyn liu ti sinh l du m ng thc vt, c bit ti s dng ngun du thi chin rn t qu trnh nu n; gip gim thiu c lng du thi gy nhim mi trng. Ngun nng lng ti sinh l yu t cc k quan trng v ngi ta c tnh vi mc tiu th nh hin nay, ngun nhin liu t du m s cn kit trong khong 50 nm na. -Do c ngun gc t du m ng thc vt, biodiesel khng cha cc cht c hi nh lu hunh, cc kim loi nng. V vy, y l