Clever idea! It seems like your code would benefit from a dictionary in this case, which would eliminate all those IF statements. Something like this might help to cut down on the length:

imoji = {'happy':'😀','glad':'😃','smile':'😄','joy':'😁','laugh':'😆','laughing':'😂',
'content':'☺️','cheese':'😊','angel':'😇','decent':'🙂','upside-down':'🙃','wink':'😉',
'calm':'😌','glad':'😃','lovee':'😍','kiss':'😘','yum':'😋','yummy':'😛','eww':'😝',
'ew':'😝','strange':'😜','silly':'🤪','really':'🤨','study':'🧐','nerd':'🤓','cool':'😎',
'starstruck':'🤩','party':'🥳','sly':'😏','sad':'😞','dissapointed':'😔','downhearted':'😣',
'wail':'😫','cry':'😩','weep':'😭','beg':'🥺','rage':'😤','anger':'😠','angry':'😡',
'insane':'🤬','incredible':'🤯','guilty':'😳','frozen':'🥶','cold':'🥶','horror':'😱',
'horrified':'😱','yay':'🤗','think':'🤔','embarrased':'🤭','silent':'😶','lame':'😐',
'frightened':'😬','afraid':'🙄','stunned':'😯','sleepy':'🥱','sleep':'😴','sleeping':'😴',
'drooling':'🤤','dead':'😵','sick':'🤢','barf':'🤮','toxic':'😷','hurt':'🤕','cowboy':'🤠',
'menace':'😈','monster':'👹','clown':'🤡','poop':'💩','skull':'💀','ghost':'👻',
'crossbones':'☠️','alien':'👽','enemy':'👾','robot':'🤖','jakolantern':'🎃','cat':'😺',
'wave':'👋','hand':'🤚','highfive':'🖐','spok':'🖖','perfect':'👌','small':'🤏','up':'☝️',
'down':'👇','right':'👉','left':'👈','awesome':'👍','like':'👍','dislike':'👎','punch':'🤛',
'clap':'👏','brain':'🧠','hands':'👐','arm':'💪','leg':'🦵','foot':'🦶','ear':'👂',
'hear':'👂','hands':'👐','nose':'👃','teeth':'🦷','tooth':'🦷','bones':'🦴','look':'👀',
'eye':'👁','tongue':'👅','lips':'👄','blood':'🩸','smooch':'💋','family':'👨‍👩‍👧‍👦','dude':'👱‍♂️',
'man':'👱‍♂️','gal':'👩‍🦳','woman':'👩‍🦳','girl':'👧','boy':'👦','baby':'👶','is':'=','for':'4',
'four':'4','the':'❕','soon':'🔜','food':'🌮','water':'💧','bob':'🧸','a':'🅰️','squid':'🦑',
'squids':'🦑','cookie':'🍪','how':'⁉️','are':'®️','can':'🤨','you':'🗣','eat':'😋',
'pizza':'🍕','nasty':'🤬'}

while True:
  sentence = input("Sentence you would like to be translated into Emoji:   ")
  out = []
  b = sentence.lower()
  l = b.split()
  for x in l:
    if x in imoji.keys():
        out.append(imoji[x])
    else:
        out.append(x)
  x = ' '.join(out)
  print(x)

cool!!

(i was searching emoji and i found this)

nice!