Lub catalyst muaj txiaj ntsig zoo uas hloov cov roj propane rau hauv hydrocarbons hnyav tau tsim los ntawm Saudi Arabia King Abdullah University of Science thiab Technology. (KAUST) researchers. Nws ua kom nrawm nrawm rau cov tshuaj tiv thaiv tshuaj hu ua alkane metathesis, uas tuaj yeem siv los tsim cov kua roj.

Lub catalyst rearranges propane, uas muaj peb carbon atoms, mus rau lwm yam molecules, xws li butane (muaj plaub carbons), pentane (nrog tsib carbons) thiab ethane (nrog ob carbons). "Peb lub hom phiaj yog los hloov qis qis molecular alkanes mus rau qhov muaj txiaj ntsig zoo ntawm cov alkanes," said Manoja Samantaray los ntawm KAUST Catalysis Center.

Nyob rau hauv lub plawv ntawm lub catalyst yog cov tebchaw ntawm ob hlau, titanium thiab tungsten, uas yog anched rau ib tug silica nto ntawm oxygen atoms. Lub tswv yim siv yog catalysis los ntawm kev tsim. Cov kev tshawb fawb yav dhau los tau pom tias monometallic catalysts tau koom nrog ob txoj haujlwm: alkane rau olefin thiab tom qab ntawd olefin metathesis. Titanium raug xaiv vim nws lub peev xwm los qhib CH daim ntawv cog lus ntawm paraffins los hloov lawv mus rau olefins, thiab tungsten raug xaiv rau nws cov haujlwm siab rau olefin metathesis.

Txhawm rau tsim cov catalyst, pab pawg ua kom sov silica kom tshem tawm cov dej ntau li ntau tau thiab tom qab ntawd ntxiv hexamethyl tungsten thiab tetraneopentyl titanium, tsim cov hmoov daj daj. Cov kws tshawb fawb tau kawm cov catalyst siv nuclear magnetic resonance (NMR) spectroscopy los qhia tias tungsten thiab titanium atoms nyob ze heev ua ke ntawm silica nto, tej zaum ze li ≈0.5 nanometers.

Cov kws tshawb fawb, coj los ntawm Tus Thawj Coj ntawm lub chaw Jean-Marie Basset, tom qab ntawd sim cov catalyst los ntawm cua sov rau 150 ° C nrog propane rau peb hnub. Tom qab ua kom zoo dua cov tshuaj tiv thaiv - piv txwv li, los ntawm kev tso cai rau cov propane kom ntws tsis tu ncua ntawm cov catalyst - lawv pom tias cov khoom tseem ceeb ntawm cov tshuaj tiv thaiv yog ethane thiab butane thiab txhua khub ntawm tungsten thiab titanium atoms tuaj yeem ua rau qhov nruab nrab ntawm 10,000 cycles ua ntej. poob lawv txoj haujlwm. Qhov "tus lej hloov pauv" no yog qhov siab tshaj plaws uas tau tshaj tawm rau cov tshuaj tiv thaiv propane metathesis.

Qhov kev vam meej ntawm catalysis los ntawm kev tsim, cov kws tshawb fawb qhia, yog vim muaj kev sib koom ua ke ntawm ob lub hlau. Ua ntej, ib lub titanium atom tshem tawm hydrogen atoms los ntawm propane los ua propene thiab tom qab ntawd ib tug nyob sib ze tungsten atom lov qhib propene ntawm nws cov carbon-carbon ob daim ntawv cog lus, tsim fragments uas yuav recombine rau lwm yam hydrocarbons. Cov kws tshawb fawb kuj pom tias cov hmoov catalyst uas tsuas muaj tungsten lossis titanium ua tau zoo heev; txawm tias thaum ob cov hmoov no tau sib xyaw ua ke, lawv qhov kev ua tau zoo tsis sib haum rau kev sib koom tes catalyst.

Pab neeg vam tias yuav tsim kom muaj ib qho zoo dua catalyst nrog tus lej ntau dua, thiab lub neej ntev dua. "Peb ntseeg tias yav tom ntej, kev lag luam tuaj yeem siv peb txoj hauv kev los tsim cov roj av alkanes thiab feem ntau ntawm catalysis los ntawm kev tsim," Samantaray hais.