Catalytic cov tshuaj tiv thaiv cov piv txwv. Homogeneous thiab heterogeneous catalysis

Science News for KIDS - qhov kev kawm ntawm yam thiab lawv transformations, raws li zoo raws li cov txheej txheem rau lawv npaj. Txawm nyob rau hauv lub tsev kawm ntawv qhov kev pab cuam yog suav tias yog xws li ib qho tseem ceeb qhov teeb meem, ob hom kev tshua. Classification, uas cov menyuam kawm ntawv nkag tau mus rau qhov yooj yim npaum li, yuav siv sij hawm mus rau hauv tus account qhov kev hloov ntawm lub oxidation theem txaus, thiab thiaj li cov txheej txheem mechanism. D. Tsis tas li ntawd, tag nrho cov tshuaj dab raug muab faib ua catalytic thiab uas tsis yog-catalytic tshua. Piv txwv ntawm transformations uas tshwm sim nrog rau catalyst raws li ib tug txiv neej nyob rau hauv lub neej txhua hnub: fermentation, putrefaction. Tsis-catalytic hloov dua siab tshiab, peb muaj ntau heev.

Yuav ua li cas yog ib lub hauv paus

Qhov no tshuaj, uas yog yuav hloov tus nqi ntawm cov tshuaj tiv thaiv, tab sis nws tus kheej nws tsis yog muab kev koom tes. Nyob rau hauv lub rooj plaub uas lub catalyst yuav siv sij hawm qhov chaw ntawm tus txheej txheem acceleration, nws yog hais txog mus rau lub zoo catalysis. Nyob rau hauv cov ntaub ntawv uas, yog hais tias tus ntxiv neeg sawv cev nyob rau hauv tus txheej txheem thiaj li cov tshuaj tiv thaiv tus nqi, nws yog hu ua ib tug inhibitor.

hom catalysis

Homogeneous thiab heterogeneous catalysis txawv nyob rau hauv theem, nyob rau hauv uas muaj cov pib cov ntaub ntawv. Yog hais tias starting lub Cheebtsam, coj mus rau kev sib tshuam, xws li cov catalyst, yog nyob rau hauv tib ua ib pawg xeev, ntws homogeneous catalysis. Nyob rau hauv lub rooj plaub uas cov tshuaj tiv thaiv yog kawm los ntawm txawv theem ntawm teeb meem, yog ua kev catalysis.

Lub selectivity ntawm qhov kev txiav txim

Catalysis yog tsis yog ib tug txhais tau tias ntawm kev txhim kho cov kev kawm ntawv ntawm cov khoom, nws muaj ib tug zoo ntxim rau qhov zoo ntawm cov khoom. Ib tug zoo xws li cov phenomenon yuav tau piav los ntawm qhov tseeb hais tias vim ib tug xim (xim) kev txiav txim ntawm feem ntau catalysts yog ceev los ntawm cov ncaj cov tshuaj tiv thaiv txo sab dab. Thaum kawg, cov khoom tau muaj ib tug ntau dua kev coj dawb huv yog tsis tsim nyog mus ntxiv purify substance. Lub selectivity ntawm qhov kev txiav txim ntawm lub catalyst muab zoo yuav txo tau ntawm uas tsis yog-tsim nqi ntawm raw cov ntaub ntawv, zoo economic cov kev pab cuam.

Qhov zoo ntawm daim ntawv thov nyob rau hauv zus tau tej cov catalyst

Yuav ua li cas lwm tus yog yus muaj los ntawm catalytic cov tshuaj tiv thaiv? Piv txwv saib nyob rau hauv ib tug pa high school, qhia tau tias kev siv ntawm cov catalyst tso cai tus txheej txheem ntawm sab kub. Sim kawm qhia tau tias nws yuav siv tau los suav rau ib tug tseem ceeb yuav txo tau nyob rau hauv cov nqi zog. Qhov no yog tshwj xeeb yog ib qho tseem ceeb nyob rau hauv lub tam sim no tshwm sim, thaum muaj ib tug tsis txaus ntawm lub zog pab nyob rau hauv lub ntiaj teb no.

Piv txwv ntawm catalytic manufactures

Uas kev lag luam siv cov catalytic cov tshuaj tiv thaiv? Piv txwv li cov nroj tsuag: zus tau tej cov nitric thiab sulfuric acids, hydrogen, ammonia, polymers thiab ua roj. Lug siv catalysis nyob rau hauv qhov kev npaj ntawm cov organic acids, monohydric thiab polyhydric alcohols, phenol resins, dyes, tshuaj.

Yuav ua li cas yog lub catalyst

Lub catalysts yuav pab ntau yam tam sim no nyob rau hauv lub periodic system ntawm tshuaj ntsiab Dmitriya Ivanovicha Mendeleeva, thiab lawv lub tebchaw. Ntawm cov feem ntau accelerators cais: npib tsib xee, hlau, platinum, cobalt, alumosilicates, manganese oxides.

nta catalysts

Nyob rau hauv tas li ntawd mus rau lub xim txiav txim catalysts muaj zoo cov neeg kho tshuab zog, lawv yuav tiv taus catalytic tshuaj lom, yooj yim regenerated (rov qab los).

Cov theem ntawm catalytic homogeneous tshua raug muab faib mus rau hauv roj theem thiab theem ua kua.

Ib tug los ze zog saib nyob rau hauv cov hom kev tshua. Nyob rau hauv kev daws teeb meem ntawm cov tshuaj hloov dua siab tshiab tsuj roj protrude hydrogen cations H +, puag hydroxide ions OH-, hlau cations, M +, thiab cov tshuaj uas txhawb lub tsim ntawm cov dawb radicals.

Lub essence ntawm catalysis

Mechanism catalysis los ntawm reacting acids thiab bases yog hais tias muaj yog ib tug pauv ntawm cov interacting tshuaj thiab catalyst zoo ions (protons). Yog li intramolecular transformations coj qhov chaw. Rau no hom ntawm cov tshuaj tiv thaiv yog:

• lub cev qhuav dej (dej uncoupling);
• co (txuas dej lwg me me);
• esterification (tsim ntawm ester los ntawm alcohols thiab carboxylic acids);
• polycondensation (polymer tsim los ntawm cleavage nrog dej).

Lub hom phiaj ntawm catalysis piav tsis tau tsuas yog cov txheej txheem, tab sis kuj tau sab transformation. Nyob rau hauv cov ntaub ntawv ntawm ib tug ua kev catalysis txheej txheem ntaub ntawv ib daim theem tsuj roj, muaj ib co catalytic zog rau ntawm qhov chaw cov ntsiab lus ntawm cov reactants los yog tag nrho saum npoo yog muab kev koom tes.

Muaj yog ib tug microheterogeneous txheej txheem uas yuav nrhiav ib tug catalyst nyob rau hauv ib tug colloidal lub xeev. Qhov kev xaiv no yog ib tug hloov lub xeev los ntawm homogeneous rau heterogeneous catalysis siab. Feem ntau ntawm cov dab no tshwm sim ntawm gaseous tshuaj siv khoom catalysts. Tej zaum lawv yuav nyob rau hauv daim ntawv ntawm pellets, ntsiav tshuaj, cov nplej.

Faib catalysis nyob rau hauv cov xwm

Enzyme catalysis yog dav faib nyob rau hauv cov xwm. Nws hais ntawm biocatalysts synthesis ntawm cov protein molecules, metabolism ua nyob rau hauv uas muaj sia nyob. Tsis muaj leej twg lom dab uas muaj sia nyob, tsis txaj muag deb ntawm lub catalytic cov tshuaj tiv thaiv. Piv txwv ntawm tseem ceeb heev dab: synthesis ntawm cov amino acids los ntawm cov nqaijrog hais rau tus kab mob; lub neej puas ntawm cov nqaijrog, cov nqaijrog, carbohydrates.

catalysis algorithm

Xav txog cov mechanism ntawm catalysis. Qhov no txoj kev tshwm sim nyob rau hauv qhov ntxeem tau khoom accelerators tshuaj sis, nws muaj ob peb yam yooj yim cov kauj ruam:

• diffusion ntawm lub reactants mus rau qhov chaw ntawm lub catalyst nplej los ntawm cov kwj ntawm cov ntsiav;
• diffusion ntawm reactants mus rau hauv lub catalyst pores;
• chemisorption (tshuab txais adsorption) rau ntawm qhov chaw ntawm lub tshuaj tsuj roj reacting nrog lub advent ntawm nto tshuaj - tshuab txais ceg "catalyst reagents";
• rearrangement ntawm atoms nrog qhov tshwm sim ntawm qhov chaw ob peb ua ke "catalyst-product";
• diffusion nyob rau hauv lub pores ntawm tus tsuj roj ntawm cov tshuaj tiv thaiv cov khoom;
• khoom diffusion ntawm tus nto ntawm lub grain txaus nyob rau hauv cov tshuaj tiv thaiv tsuj roj tub ntxhais.

Catalytic thiab uas tsis yog-catalytic tshua yog li ntawd, tseem ceeb heev uas zaum saum lub xyoo mus ntxiv cov kev tshawb fawb nyob rau hauv cov cheeb tsam no.

Thaum homogeneous catalysis muaj yog tsis muaj yuav tsum tau tsim tshwj xeeb designs. Enzyme catalysis nyob rau hauv heterogeneous variant yuav siv cov ntau haiv neeg thiab tej khoom. Rau nws txaus tsim tshwj xeeb hu kiag li lawm, subdivided tshaj rau qhov chaw hu (rau hauv cov hlab, nyob rau cov phab ntsa hauv lub catalyst meshes); ib lub lim txheej; slurry txaj; pulverized nrog ib tug mus catalyst.

Thaum tshav kub kub hloov lwm lub tsev nyob rau hauv lub apparatus yog siv nyob rau hauv ntau txoj kev:

• los ntawm thov cov chaw taws teeb (lwm) thaum tshav kub kub exchangers;
• ntawm tshav kub exchangers, kos nyob rau hauv ib tug hu rau apparatus.

Ntsuam xyuas cov mis ntawm Science News for KIDS, yuav pom xws tshua nyob rau hauv uas ib tug catalyst ua raws li ib tug ntawm zaum kawg khoom, uas yog tsim nyob rau thaum lub sij hawm cov tshuaj sis ntawm cov thawj zaug Cheebtsam.

Tej dab no yog hu ua autocatalytic, lub phenomenon nyob rau hauv Science News for KIDS hu ua autocatalysis.

Ceev ntau cov kev sib tshuam vim lub muaj nyob rau hauv cov tshuaj tiv thaiv sib tov ntawm tej yam tshuaj. Lawv cov qauv Science News for KIDS feem ntau overlooked, yog hloov los ntawm lo lus "catalyst" los yog nws cov tsiaj ntawv rau qhov no. Lawv tsis muaj xws li cov zaum kawg stereochemistry ntawm kab zauv, txij li thaum lawv, tom qab kawm tiav ntawm cov tshuaj tiv thaiv tsis hloov los ntawm cov quantitative taw tes ntawm view. Nyob rau hauv tej rooj plaub, txaus me me ntawm yam uas ho muaj kev cuam tshuam rau tus nqi ntawm cov txheej txheem. Nws yog permissible thiab lub sijhawm xws li thaum tus tsuj roj tshuaj sis nws tus kheej ua cov tshuaj tiv thaiv txog ntsha.

Lub essence ntawm lub catalyst cawv rau cov kev hloov tus nqi ntawm cov tshuaj txheej txheem yog hais tias lub yam khoom uas yog muaj nyob rau hauv nyob tus yeees ntawm cov active, thiab yog li ntawd hloov lub ua kom lub zog ntawm cov tshuaj sis raug zoo.

Nyob rau hauv lub lwj ntawm lub complex catalyst lwm yog cai. Kab hauv qab no hais tias nws yuav tsis tau siv, yuav nyob twj ywm unchanged tom qab tus nqi ntawm cov kev sis raug zoo. Nws yog vim li no yog txaus me me kom muaj nuj nqis ntawm lub active tshuaj yuav hnov mob nrog lub substrate (cov tshuaj tiv thaiv reagent). Nyob rau hauv kev muaj tiag, ib me ntsis nyiaj ntawm catalyst nyob rau hauv cov tshuaj dab cuaj kaum noj, raws li tej zaum yuav ntau theem nrab dab: nws lom txheej txheem tsis tau, cov kev hloov ntawm qhov chaw lub xeev ntawm cov khoom catalyst. Formula ntawm Science News for KIDS tsis koom nrog ris catalyst.

xaus

Cov tshuaj tiv thaiv, uas muab kev koom tes rau hauv lub active ingredient (catalyst) koos ib tug neeg, dua li lawv ntws nyob rau hauv nws lub cev. Homogeneous tshua muaj ntau ntau tshaj ua kev sis raug zoo. Nyob rau hauv txhua rooj plaub, xub thawj tus tsim ntawm intermediate ceg, uas yog tsis ruaj tsis khov, maj mam zom thiab muaj lwm (restoration) ntawm tus tsuj roj ntawm cov tshuaj txheej txheem. Piv txwv li, tus sis ntawm metaphosphoric acid nrog poov tshuaj persulfate li catalyst ua hydriodic acid. Thaum ntxiv mus rau lub reactants tsim ib tug daj tshuaj. Raws li peb txoj kev ua tus kawg ntawm tus txheej txheem coloration fades. Raws li ib nrab cov khoom nyob rau hauv cov ntaub ntawv no yog iodine, thiab cov txheej txheem yuav siv sij hawm qhov chaw nyob rau hauv ob ua sawv. Tab sis sai li sai tau raws li metaphosphoric acid yog tsim catalyst yog rov qab mus rau nws cov thawj lub xeev. Catalysts yog indispensable nyob rau hauv kev ua lag luam, lawv pab rau accelerate lub transformation kom tau high-quality khoom ntawm cov tshuaj tiv thaiv. Yog tsis tau tsis muaj lawv cov kev koom tes thiab biochemical dab nyob rau hauv lub cev.