01763262333

Temperature Programmed Desorption (TPD) Temperature Programmed Reduction (TPR) Temperature Programmed Oxidation (TPO) Our    temperature    programmed    analytical    options    are    chemisorption analyses   used   to   investigate   desorption,   oxidation   and   reduction   as   a function   of   temperature.   Traditionally   these   analytical   techniques   have been   applied   to   catalysis   fields,   where   the   study   of   surface   reactions with   temperature   are   fundamental   to   the   development   of   high   efficiency systems   and   to   their   re-generation.   Temperature   programmed   analyses are    also    beneficial    to    other    systems    where    surface    reactions    occur during   th eir   use,   for   example   in   the   study   of   re-activation   conditions   of adsorbents and filter systems.   Temperature Programmed Desorption (TPD) At    MCA    we    use    our    Micromeritics    3Flex    Chemi    TCD    instrument    for temperature   programmed   desorption.   This   is   usually   undertaken   under ambient   conditions   of   pressure,   replicating   those   typically   found   during normal   applications   of   materials.   Samples   are   pre-treated   to   clean   their surfaces   before   the   desired   gas   is   chemically   adsorbed   to   the   active   sites to   the   point   of   saturation.   The   temperature   of   the   chemisorption   stage can   be   selected   so   that   the   usual   industrial   application   is   replicated   if appropriate.      Temperature   is   then   increased   at   a   steady   rate   with   inert gas   flow   over   the   sample   and   the   desorption   of   the   chemically   adsorbed species    measured    using    a    Thermal    Conductivity    Detector    (TCD).    The temperature    at    which    desorption    occurs    and    the    quantity    of    gas desorbed    provides    valuable    information    for    determining    the    number and   heterogeneity   of   active   sites,   the   strength   of   chemisorption   and conditions for re-generation of samples. Temperature Programmed Reduction (TPR) TPR   is   used   to   investigate   the   reducibility   of   a   sample,   for   example   metal oxide     supported     catalysts,     zeolites     and     hydro-cracking     catalysts, although     the     reduction     of     many     different     compounds     can     be investigated.   The   analytical   process   typically   involves   heating   a   sample   in a   stream   of   reducing   gas,   usually   hydrogen   balanced   with   an   inert   gas. Hydrogen   usage   caused   by   the   reduction   of   the   sample   is   measured   by   a TCD,    the    temperature    range    of    reduction    is,    therefore,    established. Furthermore,    since    the    TCD    is    precisely    calibrated,    the    volume    of hydrogen consu med can be calculated.    Temperature Programmed Oxidation (TPO) TPO   is   particularly   suited   to   the   study   of   metallic   catalysts,   for   example those   used   for   the   oxidation   of   organic   compounds.   TPO   provides   a measure   of   the   extent   to   which   a   catalyst   can   be   re-oxidised.   The   most common   analytical   method   involves   fully   reducing   a   the   metal   or   metal oxide   catalyst   sample   and   then   heating   it   at   a   constant   rate   either   in   a steady   flow   of   an   oxidising   gas   mixture   or   with   pulses   of   the   oxidising gas   mixture.   The   passage   of   the   oxidising   gas   mixture   (O2   balanced   with an   inert   carrier)   through   the   sample   cell   is   measured   by   a   TCD,   allowing the   temperature   at   which   the   sample   is   oxidised   to   be   found.   Precise calibration   of   the   TCD   also   allows   for   the   oxygen   uptake   by   the   sample   to be quantified.